An electret condenser microphone is provided that can reduce parasitic capacitance and realize enhanced sensitivity. The electret condenser microphone includes a capacitor section including a fixed electrode having an electret member and a diaphragm electrode, a casing section housing the capacitor section, a circuit board including a converter circuit 4 for converting variations of capacitance of the capacitor section caused by vibrations of the diaphragm electrode to electric signals for output, and conducting elements for making the capacitor conductive with the circuit board, in which the casing section has a shape as viewed from top different from a shape of the capacitor as viewed from top to provide different distances between outer sides of the capacitor section and the casing section circumferentially of the capacitor section as viewed from top.