A fuel cell power supply includes a fuel cell voltage detection means which detects a terminal-to-terminal voltage of the fuel cell; an internal resistance calculation element configured to supply electric power from a battery to a motor via a second DC-DC converter and configured to calculates a resistance value of an internal resistance of the fuel cell on the basis of a detection voltage of the fuel cell in a state where a current output of the fuel cell is stopped, a detection voltage of a terminal-to-terminal voltage of the fuel cell in a state where the output current of the fuel cell is adjusted to a value, and the value; and a deterioration level determination element configured to determines a deterioration level of the fuel cell on the basis of a change in the resistance value of the internal resistance of the fuel cell.