An electromagnetic induction power generator includes a magnetic core attachable to a power transmission/distribution line, a power generating coil wound around the magnetic core, and a switching power supply circuit that converts AC appearing at both ends of the power generating coil into DC. The switching power supply circuit stops its switching operation based on a DC voltage level. The stop of the switching operation increases reactive power, allowing a stable power generating operation, i.e., a stable supply of active power irrespective of the amount of current flowing through the power transmission/distribution line. In addition, the amount of the reactive power can be finely adjusted based on the length of a period during which the switching operation is stopped, allowing a finer control of the reactive power.