To provide a power source circuit capable of charging an electric storage element by avoiding an operation of a protective circuit incorporated in a battery.

The power source circuit 100 is connected to the battery 200 having the protective circuit 210 for shutting off an output when a current output of a predetermined overcurrent detected value or more is sensed. The power source circuit 100 comprises the electric storage element 10 charged by the battery 20 and used as an auxiliary power source, current limiting transistors Tr1, Tr2 and Tr3 for limiting the current output of the battery 200 to a power source current I of less than the overcurrent detected value, and a voltage detector 50 for detecting a terminal voltage of the element 10. In this case, the detector 50 charges the element 10 while switching the limiting transistor to be turned on so that a limit of the current I is alleviated as the terminal voltage of the element 10 is raised.