The present invention is an electret condenser microphone that includes an electro-acoustic transducer (M) having an electret portion (E) including a diaphragm (6) acting as an electrode and a stationary electrode (2, 25) disposed in opposition to the diaphragm (6), and a FET (10) effecting an impedance conversion on an output from the electro-acoustic transducer (M) and then outputting the converted output on a signal line (L). A capacitor (11) and a varistor (12) are provided in parallel between the signal line (L) and a ground (18) and a resistor (13) is incorporated in series in the signal line (L).