Each unit pixel has a photodiode PD, an amplifying MOS transistor T1 having its gate connected to the cathode of the photodiode PD, and a MOS transistor T2 having its source connected to the node between the photodiode PD and the gate of the MOS transistor T1. Forming only two MOS transistors other than a photodiode PD functioning as a photoelectric converter helps improve the open-area ratio.