A solid-state imaging device comprising: a photon detector (D) that operates in a Geiger mode and outputs an analog output signal as a result of an avalanche amplification in accordance with the incidence of a photon; a quench element (Mq) that causes the photon detector to transition to a non-Geiger mode in which the avalanche amplification does not occur; and a signal processing circuit that performs a predetermined process on the output signal, characterized by a control unit that is supplied with a control signal (CLK) and a digital signal which is shaped into a pulse-like waveform from the analog output signal from the photon detector and switches, in accordance with the control signal and the digital signal, the quench element between a state in which the quench element has a relatively low resistance and the photon detector detects the photon in the Geiger mode, and a hold state in which the quench element has a relatively high resistance and a potential of a node between the photon detector and the quench element is controlled to hold the photon detector in the non-Geiger mode, wherein the control unit switches the quench element from the low resistance state to the high resistance state when the photon detector transitions from the Geiger mode to the non-Geiger mode, and then switches the quench element from the high resistance state to the low resistance state; the control signal is a periodic signal whose signal value changes periodically from a first level to a second level; and the signal processing circuit performs the predetermined process in synchronization with the control signal. a photon detector (D) that operates in a Geiger mode and outputs an analog output signal as a result of an avalanche amplification in accordance with the incidence of a photon; a quench element (Mq) that causes the photon detector to transition to a non-Geiger mode in which the avalanche amplification does not occur; and a signal processing circuit that performs a predetermined process on the output signal, characterized by a control unit that is supplied with a control signal (CLK) and a digital signal which is shaped into a pulse-like waveform from the analog output signal from the photon detector and switches, in accordance with the control signal and the digital signal, the quench element between a state in which the quench element has a relatively low resistance and the photon detector detects the photon in the Geiger mode, and a hold state in which the quench element has a relatively high resistance and a potential of a node between the photon detector and the quench element is controlled to hold the photon detector in the non-Geiger mode, wherein the control unit switches the quench element from the low resistance state to the high resistance state when the photon detector transitions from the Geiger mode to the non-Geiger mode, and then switches the quench element from the high resistance state to the low resistance state; the control signal is a periodic signal whose signal value changes periodically from a first level to a second level; and the signal processing circuit performs the predetermined process in synchronization with the control signal. <EOS>