PURPOSE: To obtain a transducer which is flat and small in size by providing a magnetic material for operating an electromagnetic force on a magnet, on a virtual plane being in an equal distance from two magnetic pole surface of the magnet, and providing an operating gap so as to be orthogonal to the vibrating direction of the magnet.

CONSTITUTION: On a virtual plane L being in an equal distance form magnetic pole surfaces 11A, 11B of a magnet, a magnetic material 12 which becomes an electromagnet is formed so as to be positioned through a small gap G. An electromagnetic coil 13 for magnetizing the magnetic material 12 is provided. In this state, when a current is made to flow to the coil 13, the tip of the magnetic material 12 is magnetized to an N pole or an S pole, and between said material and a magnet 11, an electromagnetic force is generated. As a result, the magnet 11 is supported by an elastic plate 14 and moved in the upper and lower directions, and an acoustic wave is generated effectively through a diaphragm 16. In this way, the whole transducer become flat and small in size.