According to one embodiment, the pixel driving circuit causes the amplifying transistor to form a source follower circuit without applying a bias voltage to the vertical signal line and connects the FD to the power source. Thereafter, the pixel driving circuit separates the current source from the vertical signal line to cancel the source follower circuit, applies a bias voltage to the vertical signal line so that the voltage of the FD is raised when the brightness of the subject is higher than the reference value, and the voltage of the FD is lowered when the brightness of the subject is lower than the reference value, and turns on the read transistor. The pixel driving circuit turns off the read transistor, and then connects the current source to the vertical signal line, and causes the amplifying transistor to form the source follower circuit.