In a light detection device, the semiconductor substrate has first and second main surfaces facing each other. The semiconductor substrate includes a plurality of cells. Each of the plurality of cells includes at least one avalanche photodiode. The plurality of pad electrodes are arranged on the first main surface so as to be spaced apart from the plurality of cells. The plurality of wiring portions are arranged on the first main surface. Each of the plurality of wiring portions connects the cell and the pad electrode corresponding to each other. The semiconductor substrate includes a peripheral carrier absorbing portion configured to absorb carriers located at a periphery of the peripheral carrier absorbing portion. The peripheral carrier absorbing portion is provided around each pad electrode and each wiring portion when viewed from a direction perpendicular to the first main surface.