A power supply system includes multiple power supply devices including a first power supply device and a second power supply device that are connected in common to a load. The first power supply device calculates control information for controlling voltage or current to be output to the load and source information for obtaining the control information, and controls the output to the load based on the calculated control information while transmitting the source information to the second power supply device. The second power supply device receives the source information transmitted from the first power supply device, calculates control information based on the received source information, and controls the output to the load while detecting current to be output from itself to the load and transmitting current information to the first power supply device.