Abstract: The present invention provides a microphone device capable of preventing a breakdown of a signal processor, which is provided in a circuit case, processing signals from a microphone unit accommodated in a unit case, and preventing production of noise in a state the unit case is detached from the circuit case. A microphone device 1 includes a unit case 3 accommodating a microphone unit 31, a circuit case 4 accommodating an input terminal receiving signals from the microphone unit, and a signal processor processing the signals input to the input terminal, the unit case 3 being detachably fixed to the circuit case 4, and a detector (38, 44) detecting the attachment or detachment between the unit case and the circuit case. The detector grounds the input terminal in response to the detection of the detachment of the unit case from the circuit case.