A semiconductor storage device has a variable-stage charge pump, and a memory cell array to which an output from an output line of the variable-stage charge pump is fed. In the variable-stage charge pump, first and second charge pumps are connected in parallel between a common input bus and a common output bus. A first n-channel MOSFET is provided on a line connecting an output terminal of the first charge pump and the common output bus, and another n-channel MOSFET is provided on a line connecting the second charge pump and the common output bus. First switches are provided between the output terminal of the first charge pump and the first n-channel MOSFET, and between the input terminal of the second charge pump and the second switch. A second switch is provided on a line connecting an input terminal of the second charge pump and the common input bus.