A light-emission responder can respond to input of sound, realizes versatility of response, and can be applied to various use forms. A microphone (110) converts a sound wave into an electric signal. An amplifying section (111) amplifies the electric signal and outputs it to an AGC section (112). The AGC section (112) adjusts the amplitude of the electric signal output from the amplifying section (111). A filter section (113) outputs an electric signal in a frequency band f1 out of the amplitude-adjusted electric signal to a comparing section (114). The comparing section (114) compares the input electric signal with a reference signal. If the voltage of the electric signal passing through the filter section (113) is higher than the reference voltage, the comparing section (114) outputs a signal “H”. When a signal “H” is output from the comparing section (114), a drive section (115) allows a light-emitting element (120) to emit light. A light-emission response output section (116) is connected to the drive section (115). When driven by the drive section (115), the light-emission response output section (116) outputs a radio wave of a predetermined frequency.