To provide a flat speaker whose vibrating body is hardly damaged from outside.

The pin 61 of a solenoid 60 moves when the current value of an acoustic signal changes, and a second magnet plate 52 moves in an X-axis direction. Repulsive force generated between a first magnet plate 42 and the second magnet plate 52 changes and the vibrating body 40 is displaced in a Z-axis direction to generate a sound from it. The vibrating body 40 facing the outside is made of metal, so there is a small risk of breakage even when an object collides against the vibrating body 40 and there is no hindrance to reproduction of the sound.