The present invention relates to a photodetector having a structure capable of increasing the dynamic range and of improving the S/N ratio for light detection. The photodetector includes a pixel including a photodiode, an integrating circuit, a CDS circuit, a selecting circuit, and a switching circuit. Charges generated by the photodiode are accumulated in an integral capacitor unit in the integrating circuit, and a first voltage value V1 corresponding to the amount of accumulated charge is outputted from the integrating circuit. The CDS circuit receives the first voltage value and outputs a second voltage value V2 corresponding to the variation of the first voltage value with reference to that at a reference time. The switching circuit compares the amount of charge generated by the photodiode with a threshold value therefor, and, based on the result of the comparison, instructs the integrating circuit to set the capacitance of the integral capacitor unit and instructs the selecting circuit to select one of the first and second voltages as an output voltage value.