An n-type region as a charge storage region of a photodiode is buried in a substrate. The interface between silicon and a silicon oxide film is covered with a high concentration p-layer and a lower concentration p-layer is formed only in the portion immediately below a floating electrode for signal extraction. Electrons generated by light are stored in the charge storage region, thereby changing the potential of the portion of the p-layer at the surface of the semiconductor region. The change is transmitted through a thin insulating film to the floating electrode by capacitive coupling and read out by a buffer transistor. Initialization of charges is executed by adding a positive high voltage to the gate electrode of a first transfer transistor such that the electrons stored in the charge storage region are transferred to the n+ region and generation of reset noise is protected.