A solid-state image pickup device that reduces the number of necessary sampling and holding capacitors has signal lines to which photoreceiving elements are connected, a clamp circuit having clamp capacitors in which one terminal is connected to the signal lines and the other terminals are short-circuited and a switch applying a reference voltage to the other terminals by the clamping operation and adding signals from the photoreceiving elements provided in the row direction along with the clamping operation, an adder which is connected to the other terminals of the clamp capacitors, adds addition signals of the respective photoreceiving element rows outputted from the other terminals and adds the signals of the plurality of photoreceiving elements provided in the column direction, an amplifier connected to the adder, a switch resetting the input side of the amplifier, and a circuit for outputting an offset of the amplifier and the signal from the amplifier.