PURPOSE: To obtain a microphone of excellent performance with high output by using a disk like hollow and flat coil of a minimum moving mass and operating it in a reciprocating strong magnetic field.

CONSTITUTION: A reference numeral 1 shows a cone diaphragm, 2 a disk like hollow and flat coil on which an insulated fine line is wounded. This is situated in an air gap formed by armature sections 4, 5. The armature sections 4, 5 are constituted by holding an upper and a lower sections of flat magnets 6, 7 by pole pieces 8, 9 and 10, 11 respectively. The polarities of the flat magnets 6, 7 are opposite so as to form counter electrodes by the pole pieces 8, 9 and 10, 11, respectively. The air gap 12 is made smaller than the thickness of the flat magnet. A reference numeral 13 designates a hollow section of the flat coil. A diameter of this hollow is substantially the thickness of the magnet. The thickness of the pole piece is substantially the height of the semicylindrical sections 13, 14 in the coil. Since the coil constituted in this manner is operated in a reciprocating strong magnetic field, an extremely efficient microphone generating system is obtained.