A power supply device outputting voltage and current to a load, comprising: a current detection unit that is configured to detect current output to the load; a voltage detection unit that is configured to detect voltage output to the load; a current information reception unit that is configured to receive current information indicative of current output from a further power supply device to the load; a calculation unit that is configured to calculate control information for controlling voltage or current to be output to the load based on the current indicated by the current information received by the current information reception unit, the current detected by the current detection unit and the voltage detected by the voltage detection unit; a first correction unit that is configured to correct the control information concerning the power supply device such that current output from the power supply device to the load and the current output from the further power supply device to the load are equalized based on the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit; a second correction unit that is configured to correct the control information concerning the further power supply device such that current output from the power supply device to the load and the current output from the further power supply device to the load are equalized based on the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit; a control unit that is configured to control voltage or current to be output to the load based on the control information corrected by the first correction unit; and a control information transmission unit that is configured to transmit the control information corrected by the second correction unit to the further power supply device wherein, the first correction unit and the second correction unit are configured to correct the control information according to a ratio of a current difference to a total current, the current difference being a difference between the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit, and the total current being a sum of the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit. a current detection unit that is configured to detect current output to the load; a voltage detection unit that is configured to detect voltage output to the load; a current information reception unit that is configured to receive current information indicative of current output from a further power supply device to the load; a calculation unit that is configured to calculate control information for controlling voltage or current to be output to the load based on the current indicated by the current information received by the current information reception unit, the current detected by the current detection unit and the voltage detected by the voltage detection unit; a first correction unit that is configured to correct the control information concerning the power supply device such that current output from the power supply device to the load and the current output from the further power supply device to the load are equalized based on the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit; a second correction unit that is configured to correct the control information concerning the further power supply device such that current output from the power supply device to the load and the current output from the further power supply device to the load are equalized based on the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit; a control unit that is configured to control voltage or current to be output to the load based on the control information corrected by the first correction unit; and a control information transmission unit that is configured to transmit the control information corrected by the second correction unit to the further power supply device wherein, the first correction unit and the second correction unit are configured to correct the control information according to a ratio of a current difference to a total current, the current difference being a difference between the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit, and the total current being a sum of the current indicated by the current information received by the current information reception unit and the current detected by the current detection unit.