diff --git a/firmware/SensorLogger.cpp b/firmware/SensorLogger.cpp
index 765094c..8bd63bd 100644
--- a/firmware/SensorLogger.cpp
+++ b/firmware/SensorLogger.cpp
@@ -2,25 +2,76 @@
 
 #include <Adafruit_AHTX0.h>
 #include <BH1750.h>
+#include <BLE2902.h>
+#include <BLEDevice.h>
+#include <BLEServer.h>
+#include <BLEUtils.h>
 #include <time.h>
 
 namespace {
+constexpr char kNusServiceUuid[] = "6E400001-B5A3-F393-E0A9-E50E24DCCA9E";
+constexpr char kNusRxUuid[] = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E";
+constexpr char kNusTxUuid[] = "6E400003-B5A3-F393-E0A9-E50E24DCCA9E";
+
 Adafruit_AHTX0 aht20;
 BH1750 bh1750;
 bool aht20Ready = false;
 bool bh1750Ready = false;
 }
 
-void SensorLogger::begin(uint8_t soilPin, const char* bluetoothName) {
+class SensorLoggerCallbacks : public BLECharacteristicCallbacks {
+public:
+  explicit SensorLoggerCallbacks(SensorLogger* logger) : logger_(logger) {}
+
+  void onWrite(BLECharacteristic* characteristic) override {
+    logger_->receiveBluetoothData(characteristic->getValue().c_str());
+  }
+
+private:
+  SensorLogger* logger_;
+};
+
+class SensorLoggerServerCallbacks : public BLEServerCallbacks {
+public:
+  void onConnect(BLEServer*) override {}
+
+  void onDisconnect(BLEServer* server) override {
+    server->startAdvertising();
+  }
+};
+
+void SensorLogger::begin(uint8_t soilPin) {
   soilPin_ = soilPin;
-  bluetoothName_ = bluetoothName;
   pinMode(soilPin_, INPUT);
   analogReadResolution(12);
 
   aht20Ready = aht20.begin();
   bh1750Ready = bh1750.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
 
-  bluetooth_.begin(bluetoothName);
+  uint64_t mac = ESP.getEfuseMac();
+  char name[14];
+  snprintf(name, sizeof(name), "EnvLog-%05llX", mac & 0xFFFFF);
+  bluetoothName_ = name;
+  BLEDevice::init(bluetoothName_.c_str());
+
+  server_ = BLEDevice::createServer();
+  server_->setCallbacks(new SensorLoggerServerCallbacks());
+  BLEService* service = server_->createService(kNusServiceUuid);
+  BLECharacteristic* rxCharacteristic = service->createCharacteristic(
+    kNusRxUuid, BLECharacteristic::PROPERTY_WRITE | BLECharacteristic::PROPERTY_WRITE_NR);
+  rxCharacteristic->setCallbacks(new SensorLoggerCallbacks(this));
+  txCharacteristic_ = service->createCharacteristic(
+    kNusTxUuid, BLECharacteristic::PROPERTY_NOTIFY);
+  txCharacteristic_->addDescriptor(new BLE2902());
+  service->start();
+
+  BLEAdvertising* advertising = BLEDevice::getAdvertising();
+  advertising->addServiceUUID(kNusServiceUuid);
+  advertising->setScanResponse(true);
+  advertising->setMinPreferred(0x06);
+  advertising->setMinPreferred(0x12);
+  BLEDevice::startAdvertising();
+
   readAndStore();
   lastMeasure_ = millis();
 }
@@ -73,13 +124,25 @@ void SensorLogger::readAndStore() {
 }
 
 void SensorLogger::processBluetooth() {
-  while (bluetooth_.available()) {
-    char character = static_cast<char>(bluetooth_.read());
+  while (commandBuffer_.indexOf('\n') >= 0 || commandBuffer_.indexOf('\r') >= 0) {
+    int lineEnd = commandBuffer_.indexOf('\n');
+    int carriageReturn = commandBuffer_.indexOf('\r');
+    if (lineEnd < 0 || (carriageReturn >= 0 && carriageReturn < lineEnd)) {
+      lineEnd = carriageReturn;
+    }
+    String command = commandBuffer_.substring(0, lineEnd);
+    commandBuffer_.remove(0, lineEnd + 1);
+    if (command.length() != 0) {
+      processCommand(command);
+    }
+  }
+}
+
+void SensorLogger::receiveBluetoothData(const String& data) {
+  for (size_t index = 0; index < data.length(); ++index) {
+    char character = data[index];
     if (character == '\n' || character == '\r') {
-      if (commandBuffer_.length() != 0) {
-        processCommand(commandBuffer_);
-        commandBuffer_ = "";
-      }
+      commandBuffer_ += character;
     } else if (commandBuffer_.length() < 64) {
       commandBuffer_ += character;
     }
@@ -91,7 +154,8 @@ void SensorLogger::processCommand(const String& command) {
     sendLog();
   } else if (command == "CLEAR_LOG") {
     clearLog();
-    bluetooth_.println("OK_CLEARED");
+    txCharacteristic_->setValue("OK_CLEARED\n");
+    txCharacteristic_->notify();
   } else if (command.startsWith("TIME:")) {
     unsigned long epoch = command.substring(5).toInt();
     unsigned int year;
@@ -114,28 +178,45 @@ void SensorLogger::processCommand(const String& command) {
     if (epoch != 0) {
       epochOffset_ = epoch - millis() / 1000UL;
       timeSynchronized_ = true;
-      bluetooth_.println("OK_TIME");
+      txCharacteristic_->setValue("OK_TIME\n");
+      txCharacteristic_->notify();
     } else {
-      bluetooth_.println("ERROR_TIME");
+      txCharacteristic_->setValue("ERROR_TIME\n");
+      txCharacteristic_->notify();
     }
   }
 }
 
 void SensorLogger::sendLog() {
-  bluetooth_.println("timestamp,temp,humid,light,soil,device");
+  sendNotification("timestamp,temp,humid,light,soil,device\n");
   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",
+    char line[128];
+    snprintf(line, sizeof(line), "%lu,%.2f,%.2f,%.2f,%u,%s\n",
       reading.timestamp,
       reading.temperature,
       reading.humidity,
       reading.illuminance,
       reading.soilMoisture,
-      bluetoothName_);
+      bluetoothName_.c_str());
+    sendNotification(line);
     delay(20);
   }
-  bluetooth_.println("END_LOG");
+  sendNotification("END_LOG\n");
+}
+
+void SensorLogger::sendNotification(const char* data) {
+  constexpr size_t kNotificationSize = 20;
+  uint8_t notification[kNotificationSize];
+  size_t length = strlen(data);
+  for (size_t offset = 0; offset < length; offset += kNotificationSize) {
+    size_t chunkSize = min(kNotificationSize, length - offset);
+    memcpy(notification, data + offset, chunkSize);
+    txCharacteristic_->setValue(notification, chunkSize);
+    txCharacteristic_->notify();
+    delay(10);
+  }
 }
 
 void SensorLogger::clearLog() {
diff --git a/firmware/SensorLogger.h b/firmware/SensorLogger.h
index 482cd3a..0ad9f42 100644
--- a/firmware/SensorLogger.h
+++ b/firmware/SensorLogger.h
@@ -1,7 +1,9 @@
 #pragma once
 
 #include <Arduino.h>
-#include <BluetoothSerial.h>
+
+class BLECharacteristic;
+class BLEServer;
 
 struct SensorReading {
   unsigned long timestamp;
@@ -15,7 +17,7 @@ class SensorLogger {
 public:
   static constexpr size_t kMaxLogEntries = 2000;
 
-  void begin(uint8_t soilPin, const char* bluetoothName);
+  void begin(uint8_t soilPin);
   bool update();
   const SensorReading& latest() const;
   bool hasReading() const;
@@ -26,11 +28,14 @@ private:
   void readAndStore();
   void processBluetooth();
   void processCommand(const String& command);
+  void receiveBluetoothData(const String& data);
+  void sendNotification(const char* data);
   void sendLog();
   void clearLog();
   unsigned long currentTimestamp() const;
 
-  BluetoothSerial bluetooth_;
+  BLEServer* server_ = nullptr;
+  BLECharacteristic* txCharacteristic_ = nullptr;
   SensorReading log_[kMaxLogEntries] = {};
   SensorReading latest_ = {};
   size_t logStart_ = 0;
@@ -39,6 +44,8 @@ private:
   unsigned long lastMeasure_ = 0;
   unsigned long epochOffset_ = 0;
   bool timeSynchronized_ = false;
-  const char* bluetoothName_ = "";
+  String bluetoothName_;
   String commandBuffer_;
+
+  friend class SensorLoggerCallbacks;
 };
diff --git a/firmware/firmware.ino b/firmware/firmware.ino
index 5dab087..8754b3d 100644
--- a/firmware/firmware.ino
+++ b/firmware/firmware.ino
@@ -123,7 +123,7 @@ void setup() {
   u8g2.begin();
   u8g2.enableUTF8Print(); // UTF-8（日本語）描画を有効化
 
-  sensorLogger.begin(32, kBluetoothName);
+  sensorLogger.begin(32);
   updateDisplay();
 
   // I2S ピン設定 (BCK: 27, WS: 25, DOUT: 26)