To provide a signal converter of a small-size and a low profile that minimizes the power consumption so as to extend the operating time of a portable phone or a PCS(Personal Communication Service phone) that mounts the signal converter.

The signal converter is provided with a cylindrical frame 1, a yoke 2 that has a cylindrical projection at its upper and lower parts and with many air holes vertically around the cylindrical main body, two springs 6, 16 that are placed horizontally on the inner face of the frame 1 while enclosing the upper and lower parts of the yoke 2 so as to provide elasticity to the yoke, two magnets 4, 14 that are placed at the upper part and the lower part a part from the projection of the yoke by a prescribed distance while the different polarities oppose to each other at the upper and lower parts of the yoke 2, and two female coils 7, 17 that are placed extending to a space between a diaphragm 24 and a grill 9 mounted to the upper and lower parts of the frame 1 and the respective magnets and the projections of the yoke, receive an external input of drive power with a prescribed frequency and generate a magnetic force for production of vibration or sound.