A power supply device (10) includes a plurality of constant current output circuits (14) that can supply power to a load (12). The constant current output circuit (14) includes a pulse generation unit (20) that generates a pulse voltage, and a communication unit (34) that transmits and receives drive information, between the constant current output circuit (14) and the other constant current output circuit (14). When an abnormality occurs in the constant current output circuit (14) supplying power to the load (12) and the constant current output circuit (14) supplying power to the load (12) is switched to the other constant current output circuit (14), the other constant current output circuit (14) drives the pulse generation unit (20) by using the drive information that has been received through the communication unit (34) from the power supply means having supplied power to the load.