PURPOSE: To supply power automatically to an electronic circuit at head mount by connecting a switch mechanism whose circuit is closed with a pressure exerted to its housing at head mount to a power supply circuit.

CONSTITUTION: Electrodes 11, 12 are opposed to each other at an inside of a raised part 9 and a tip of a raised part 10 to form a switch mechanism in which the electrodes 11, 12 are in contact when a housing 1 and a buffle plate 3 are close to each other, and the electrodes 11, 12 are connected to a power supply circuit via a lead wire. When the user mounts the headphone to its head, a pressure is exerted to the housing by the elasticity of a head band to approach the housing 1 and the buffle plate 3. Thus, since the switch mechanism comprising the electrodes 11, 12 is closed by the approaching force by selecting the elastic force of the spring 15 smaller than the approaching force, power is supplied as a wireless headphone and when the user removes the headphone from the head, the electrodes 11, 12 are parted and the switch mechanism is kept open.