PURPOSE: To provide the power supply apparatus of a satellite in which the heat values of shunt devices can be kept constant regardless of the distance from the sun and the number of the operating shunt devices can be reduced.

CONSTITUTION: Shunt devices 10 (20 and 30) are connected to solar cells 10 (21, 24 and 31) in parallel. Further, a plurality of cell blocks 1, 2 and 3 which are connected to each other through a bus-bar 4 and detecting circuits 5 and 6 which control the upper limit voltage of the output voltage of the bus-bar 4 and operate the shunt device 10 (20 or 30) provided in the one battery block 1 (2 or 3) among a plurality of the battery blocks 1, 2 and 3 are provided. In a plurality of the cell blocks 1, 2 and 3, the numbers of the solar cells 11 (21, 24 and 31) which are connected to the respective shunt devices 10 (20 and 30) are different.