It is an object of the present invention to provide a fuel cell power supply device that can realize a reduction in size and improvement of durability of an accumulating unit while maintaining output performance that is applicable when large output is requested. The fuel cell power supply device includes: an output judging unit 31 that judges whether the output of a fuel cell 1 is equal to or higher than a predetermined level with respect to electric power requested by a load 5; and a power-supply controlling unit 30 that limits, when it is not judged that the output of the fuel cell 1 is equal to or higher than the predetermined level, the output of an accumulating unit 21 to be equal to or smaller than a first output limit value for allowing continuous output in first output time an limits, when it is judged that the output of the fuel cell 1 is equal to or higher than the predetermined level, within second output time shorter than the first output time, the output of the accumulating unit 21 to be equal to or smaller than a second output limit value, which is larger than the first output limit value, for allowing continuous output in the second output time.