A power source switching circuit for selectively connecting first and second power sources, at least one of which is a battery power source, to a load includes first and second power source connection parts for connection to the first and second power sources, a load connection part for connection to the load, first and second switch parts between each power source connection part and the load connection part, and a switching control part configured to perform a switch control of each switch part. Each switch part includes a plurality of FETs serially connected in the same direction such that a cathode side of a body diode is arranged on a load connection part side. The number of FETs is such that a sum of forward drop voltages of the body diodes exceeds the difference between a full charge voltage and a discharge voltage of the battery power source.
