Wireless power supply device

A wireless power supply device comprising:

• a power transmitting circuit board on which a power transmitting antenna is formed;
• a power supply circuit configured to supply a microwave to the power transmitting antenna;
• a power receiving circuit board on which a power receiving antenna is formed;
• a power receiving circuit configured to receive supply of power of the microwave via the power receiving antenna;
• a load configured to operate using the power supplied by the power receiving circuit;
• and
• an electrically-conductive case surrounded by an electrically-conductive plate in which the power transmitting antenna and the power receiving antenna are accommodated, wherein
• in the electrically-conductive case, a microwave radiated from the power transmitting antenna is received by the power receiving antenna, and power of the microwave is supplied to the load,
• the load is a torque sensor configured to detect a running torque of a crankshaft that rotates together with a pedal of a power-assisted bicycle,
• the torque sensor and the power receiving circuit board are fixed to the crankshaft, and
• the power transmitting circuit board on which the power transmitting antenna is formed and the power receiving circuit board on which the power receiving antenna is formed are accommodated in the electrically-conductive case fixed to a main body of the power-assisted bicycle.