A photodetector device includes an avalanche photodiode array substrate. A circuit substrate includes time measurement circuits and a clock driver. Each of the time measurement circuit includes a delay line unit, and is arranged to acquire, from an operation result of a delay line, time information indicating timing at which a pulse signal is input from a corresponding avalanche photodiode. The delay line unit is arranged to initiate an operation of the delay line in response to input of the pulse signal to the time measurement circuit, and to stop the operation of the delay line in response to input of a clock signal from a clock driver to the time measurement circuit, and is arranged to detect a time interval shorter than a cycle of the clock signal by the operation of the delay line.