diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e4cf9ec..f3a5159 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -41,6 +41,11 @@ jobs:
       - name: Install U8g2 library
         run: arduino-cli lib install "U8g2"
 
+      - name: Install sensor libraries
+        run: |
+          arduino-cli lib install "Adafruit AHTX0"
+          arduino-cli lib install "BH1750"
+
       # コンパイル実行 (output-dir を指定して構成ファイルを確実に生成)
       - name: Compile Sketch
         run: |
diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
new file mode 100644
index 0000000..765094c
--- /dev/null
+++ b/firmware/SensorLogger.cpp
@@ -0,0 +1,149 @@
+#include "SensorLogger.h"
+
+#include <Adafruit_AHTX0.h>
+#include <BH1750.h>
+#include <time.h>
+
+namespace {
+Adafruit_AHTX0 aht20;
+BH1750 bh1750;
+bool aht20Ready = false;
+bool bh1750Ready = false;
+}
+
+void SensorLogger::begin(uint8_t soilPin, const char* bluetoothName) {
+  soilPin_ = soilPin;
+  bluetoothName_ = bluetoothName;
+  pinMode(soilPin_, INPUT);
+  analogReadResolution(12);
+
+  aht20Ready = aht20.begin();
+  bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
+
+  bluetooth_.begin(bluetoothName);
+  readAndStore();
+  lastMeasure_ = millis();
+}
+
+bool SensorLogger::update() {
+  processBluetooth();
+
+  unsigned long now = millis();
+  if (now - lastMeasure_ >= kMeasureIntervalMs) {
+    lastMeasure_ = now;
+    readAndStore();
+    return true;
+  }
+  return false;
+}
+
+const SensorReading& SensorLogger::latest() const {
+  return latest_;
+}
+
+bool SensorLogger::hasReading() const {
+  return logCount_ != 0;
+}
+
+void SensorLogger::readAndStore() {
+  sensors_event_t humidityEvent;
+  sensors_event_t temperatureEvent;
+  SensorReading reading = {};
+
+  if (aht20Ready) {
+    aht20.getEvent(&humidityEvent, &temperatureEvent);
+    reading.temperature = temperatureEvent.temperature;
+    reading.humidity = humidityEvent.relative_humidity;
+  }
+  if (bh1750Ready) {
+    reading.illuminance = bh1750.readLightLevel();
+  }
+  reading.soilMoisture = analogRead(soilPin_);
+  reading.timestamp = currentTimestamp();
+  latest_ = reading;
+
+  size_t writeIndex = (logStart_ + logCount_) % kMaxLogEntries;
+  if (logCount_ == kMaxLogEntries) {
+    log_[logStart_] = reading;
+    logStart_ = (logStart_ + 1) % kMaxLogEntries;
+  } else {
+    log_[writeIndex] = reading;
+    ++logCount_;
+  }
+}
+
+void SensorLogger::processBluetooth() {
+  while (bluetooth_.available()) {
+    char character = static_cast<char>(bluetooth_.read());
+    if (character == '\n' || character == '\r') {
+      if (commandBuffer_.length() != 0) {
+        processCommand(commandBuffer_);
+        commandBuffer_ = "";
+      }
+    } else if (commandBuffer_.length() < 64) {
+      commandBuffer_ += character;
+    }
+  }
+}
+
+void SensorLogger::processCommand(const String& command) {
+  if (command == "GET_LOG") {
+    sendLog();
+  } else if (command == "CLEAR_LOG") {
+    clearLog();
+    bluetooth_.println("OK_CLEARED");
+  } else if (command.startsWith("TIME:")) {
+    unsigned long epoch = command.substring(5).toInt();
+    unsigned int year;
+    unsigned int month;
+    unsigned int day;
+    unsigned int hour;
+    unsigned int minute;
+    unsigned int second;
+    if (sscanf(command.c_str(), "TIME:[%u,%u,%u,%u,%u,%u]",
+        &year, &month, &day, &hour, &minute, &second) == 6) {
+      struct tm date = {};
+      date.tm_year = year - 1900;
+      date.tm_mon = month - 1;
+      date.tm_mday = day;
+      date.tm_hour = hour;
+      date.tm_min = minute;
+      date.tm_sec = second;
+      epoch = static_cast<unsigned long>(mktime(&date));
+    }
+    if (epoch != 0) {
+      epochOffset_ = epoch - millis() / 1000UL;
+      timeSynchronized_ = true;
+      bluetooth_.println("OK_TIME");
+    } else {
+      bluetooth_.println("ERROR_TIME");
+    }
+  }
+}
+
+void SensorLogger::sendLog() {
+  bluetooth_.println("timestamp,temp,humid,light,soil,device");
+  for (size_t index = 0; index < logCount_; ++index) {
+    size_t logIndex = (logStart_ + index) % kMaxLogEntries;
+    const SensorReading& reading = log_[logIndex];
+    bluetooth_.printf("%lu,%.2f,%.2f,%.2f,%u,%s\n",
+      reading.timestamp,
+      reading.temperature,
+      reading.humidity,
+      reading.illuminance,
+      reading.soilMoisture,
+      bluetoothName_);
+    delay(20);
+  }
+  bluetooth_.println("END_LOG");
+}
+
+void SensorLogger::clearLog() {
+  logStart_ = 0;
+  logCount_ = 0;
+}
+
+unsigned long SensorLogger::currentTimestamp() const {
+  unsigned long elapsedSeconds = millis() / 1000UL;
+  return timeSynchronized_ ? epochOffset_ + elapsedSeconds : elapsedSeconds;
+}
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
new file mode 100644
index 0000000..482cd3a
--- /dev/null
+++ b/firmware/SensorLogger.h
@@ -0,0 +1,44 @@
+#pragma once
+
+#include <Arduino.h>
+#include <BluetoothSerial.h>
+
+struct SensorReading {
+  unsigned long timestamp;
+  float temperature;
+  float humidity;
+  float illuminance;
+  uint16_t soilMoisture;
+};
+
+class SensorLogger {
+public:
+  static constexpr size_t kMaxLogEntries = 2000;
+
+  void begin(uint8_t soilPin, const char* bluetoothName);
+  bool update();
+  const SensorReading& latest() const;
+  bool hasReading() const;
+
+private:
+  static constexpr unsigned long kMeasureIntervalMs = 3600000UL;
+
+  void readAndStore();
+  void processBluetooth();
+  void processCommand(const String& command);
+  void sendLog();
+  void clearLog();
+  unsigned long currentTimestamp() const;
+
+  BluetoothSerial bluetooth_;
+  SensorReading log_[kMaxLogEntries] = {};
+  SensorReading latest_ = {};
+  size_t logStart_ = 0;
+  size_t logCount_ = 0;
+  uint8_t soilPin_ = 0;
+  unsigned long lastMeasure_ = 0;
+  unsigned long epochOffset_ = 0;
+  bool timeSynchronized_ = false;
+  const char* bluetoothName_ = "";
+  String commandBuffer_;
+};
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 067fc2c..5dab087 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -1,34 +1,23 @@
 #include "BluetoothA2DPSink.h"
 #include <Wire.h>
 #include <U8g2lib.h>
-#include <Adafruit_AHTX0.h>
-#include <BH1750.h>
 #include "NeoPixelController.h"
+#include "SensorLogger.h"
 
 const char kBluetoothName[] = "BT_Speaker5.32";
-constexpr uint8_t kSoilMoisturePin = 32;
-constexpr unsigned long kSensorUpdateIntervalMs = 1000;
 
 // I2C接続のOLED設定 (SSD1306 128x64)
 U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
 
 BluetoothA2DPSink a2dp_sink;
 NeoPixelController neoPixelController;
-Adafruit_AHTX0 aht20;
-BH1750 bh1750;
+SensorLogger sensorLogger;
 
 // 表示用変数
 String currentTitle = "未接続";
 String currentArtist = "";
 int currentVolumePercent = 0; // 音量 (0 ~ 100%)
 bool bluetoothConnected = false;
-bool aht20Ready = false;
-bool bh1750Ready = false;
-unsigned long lastSensorUpdate = 0;
-float temperature = 0.0f;
-float humidity = 0.0f;
-float illuminance = 0.0f;
-int soilMoisture = 0;
 
 // 画面全体を再描画する関数
 void updateDisplay() {
@@ -36,23 +25,17 @@ void updateDisplay() {
 
   if (!bluetoothConnected) {
     u8g2.setFont(u8g2_font_6x10_tf);
+    const SensorReading& reading = sensorLogger.latest();
 
     char sensorLine[32];
-    if (aht20Ready) {
-      snprintf(sensorLine, sizeof(sensorLine), "T:%5.1fC H:%5.1f%%", temperature, humidity);
-    } else {
-      snprintf(sensorLine, sizeof(sensorLine), "AHT20: error");
-    }
+    snprintf(sensorLine, sizeof(sensorLine), "T:%5.1fC H:%5.1f%%",
+      reading.temperature, reading.humidity);
     u8g2.drawStr(0, 12, sensorLine);
 
-    if (bh1750Ready) {
-      snprintf(sensorLine, sizeof(sensorLine), "Light: %6.1f lx", illuminance);
-    } else {
-      snprintf(sensorLine, sizeof(sensorLine), "BH1750: error");
-    }
+    snprintf(sensorLine, sizeof(sensorLine), "Light: %6.1f lx", reading.illuminance);
     u8g2.drawStr(0, 30, sensorLine);
 
-    snprintf(sensorLine, sizeof(sensorLine), "Soil: %4d", soilMoisture);
+    snprintf(sensorLine, sizeof(sensorLine), "Soil: %4u", reading.soilMoisture);
     u8g2.drawStr(0, 48, sensorLine);
     u8g2.sendBuffer();
     return;
@@ -127,24 +110,6 @@ void connection_state_changed_callback(esp_a2d_connection_state_t state, void *)
   updateDisplay();
 }
 
-void updateSensorDisplay() {
-  sensors_event_t humidityEvent;
-  sensors_event_t temperatureEvent;
-
-  if (aht20Ready) {
-    aht20.getEvent(&humidityEvent, &temperatureEvent);
-    temperature = temperatureEvent.temperature;
-    humidity = humidityEvent.relative_humidity;
-  }
-
-  if (bh1750Ready) {
-    illuminance = bh1750.readLightLevel();
-  }
-
-  soilMoisture = analogRead(kSoilMoisturePin);
-  updateDisplay();
-}
-
 void setup() {
   Serial.begin(115200);
 
@@ -158,12 +123,8 @@ void setup() {
   u8g2.begin();
   u8g2.enableUTF8Print(); // UTF-8（日本語）描画を有効化
 
-  aht20Ready = aht20.begin();
-  bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
-  analogReadResolution(12);
-
-  updateSensorDisplay();
-  lastSensorUpdate = millis();
+  sensorLogger.begin(32, kBluetoothName);
+  updateDisplay();
 
   // I2S ピン設定 (BCK: 27, WS: 25, DOUT: 26)
   i2s_pin_config_t my_pin_config = {
@@ -187,10 +148,7 @@ void setup() {
 
 void loop() {
   neoPixelController.update();
-
-  unsigned long now = millis();
-  if (!bluetoothConnected && now - lastSensorUpdate >= kSensorUpdateIntervalMs) {
-    lastSensorUpdate = now;
-    updateSensorDisplay();
+  if (sensorLogger.update() && !bluetoothConnected) {
+    updateDisplay();
   }
 }
\ No newline at end of file