To reduce the number of signals for controlling a semiconductor storage device from an external circuit in a configuration of performing suspension and return of a power source voltage.

A semiconductor storage device comprises: a storage circuit including a transistor having an oxide semiconductor in a semiconductor layer; a capacitative element storing charge for reading data held by the storage circuit; a charge storage circuit for controlling storage of charge into the capacitative element; a data detection circuit controlling a reading state of data; a timing control circuit creating a signal in a period immediately after supply of a power source voltage, for causing the charge storage circuit to store charge in the capacitative element by a signal of the power source voltage and a delayed signal of the power source voltage; and an inverter circuit outputting potential obtained by potential reversal of one electrode of the capacitative element.