A wireless electrical power supply apparatus 100 includes a first electrical power supply unit 101, a second electrical power supply unit 104, voltage control circuits 113 and 123 configured to control a first voltage difference between a first input voltage E1 and a first output voltage E2 during forward power transmission and a second voltage difference between a second input voltage E2 and a second output voltage E1 during reverse power transmission, a second switching control circuit 121, 122 configured to turn off a second transistor Q2 during the forward power transmission and thereby cause a second diode D2 to perform rectification, and a first switching control circuit 111, 112 configured to turn off a first transistor Q1 during the reverse power transmission and thereby cause a first diode D1 to perform rectification.