Abstract: In a hybrid power supply device constituted such that a secondary battery (4) is charged by a fuel battery (3) and electric power is supplied from the secondary battery (4) to a load (1), even when there are variations among residual capacities of individual unit secondary batteries (4a) constituting the secondary battery (4), the secondary battery (4) can be charged properly without causing overcharging in each of unit secondary batteries (4a). The fuel battery (3) is divided into a plurality of unit fuel batteries (3a), each consisting of a predetermined number of cells, and each unit hybrid power supply (2a) is constituted by connecting each unit fuel battery (3a) with each unit secondary battery (4a) through each charging switch (13) in parallel. The charging switch (13) is controlled independently for each unit hybrid power supply (2a) on the basis of the residual capacity of each unit secondary battery (4a) to perform charging of the unit secondary battery (4a) by the unit fuel battery (3a).