An alcohol concentration detecting device includes a smart mobile device and an alcohol detecting module. The smart mobile device includes an audio jack electrically connecting unit, a monitor unit and a first processing unit wherein the first processing unit includes an application (APP). The alcohol module includes an alcohol detecting element, a connector and a second processing unit. When the connector of the alcohol detecting module and the audio jack electrically connecting unit of the smart mobile device connect electrically, the application boots the second processing unit to let the alcohol detecting element in standby status.一種酒精濃度感測裝置,其包含一智慧型行動裝置及一酒精感測模組,該智慧型行動裝置具有一音源孔電性連接單元、一顯示單元及一第一處理單元,該第一處理單元包含一應用程式,該酒精感測模組具有一酒精感測元件、一連接件及一第二處理單元,當該酒精感測模組以該連接件與該智慧型行動裝置的該音源孔電性連接單元電性連接時,以該應用程式啟動該第二處理單元,並使該酒精感測元件處於等待感測狀態。100‧‧‧酒精濃度感測裝置110‧‧‧智慧型行動裝置111‧‧‧音源孔電性連接單元112‧‧‧顯示單元113‧‧‧第一處理單元120‧‧‧酒精感測模組121‧‧‧酒精感測元件122‧‧‧連接件123‧‧‧第二處理單元123a‧‧‧類比數位轉換器123b‧‧‧編解碼器124‧‧‧電源單元A‧‧‧應用程式
