Abstract: An automatic sterilizing device for a telephone comprises a microswitch which is controlled by a telephone cut-off press button, an IC control circuit turning off automatically the ultraviolet electric bulb power at a time, an ultraviolet electric bulb radiating the ultraviolet rays, and a safety switch controlled by the receiver of the telephone. The microswitch, bulb and IC control circuit are united in the receiver seat and the mouthpiece seat in the housing of the telephone. After using the telephone, the receiver is placed on its seat and contacts the microswitch, and then the power is provided to make the ultraviolet bulb produce ultraviolet rays to radiate the mouthpiece to sterilize the mouthpiece. In the meantime, a signal is produced to contact the delay circuit of the IC control circuit at the time of contact of the microswitch. After the set delay time, the IC control circuit automatically turns off the power of the ultraviolet bulb.