A light detecting device, comprising: a photoelectric conversion region configured to generate a photoelectric charge; a sense node, wherein the sense node is connected to the photoelectric conversion region, includes a first capacitive element, that has a larger capacitance than other capacitances in the sense node such that the capacitance of the first capacitive element is the dominant capacitance of the sense node, and holds the photoelectric charge generated by the photoelectric conversion region; a floating diffusion that includes a second capacitive element, that has a larger capacitance than other capacitances in the floating diffusion such that the capacitance of the second capacitive element is the dominant capacitance of the floating diffusion, and is configured to hold the photoelectric charge transferred from the sense node; a first transistor between the sense node and the floating diffusion, wherein the first transistor is configured to selectively connect the sense node to the floating diffusion to transfer the photoelectric charge held in the sense node to the floating diffusion; and a second transistor between the floating diffusion and a signal line, wherein the second transistor is configured to selectively cause a pixel signal of a voltage value corresponding to a charge amount of the photoelectric charge held in the floating diffusion to appear on the signal line, wherein the capacitance of the first capacitive element and the capacitance of the second capacitive element are provided so that a first value obtained by adding all other capacitances of the sense node to the capacitance of the first capacitive element matches a second value obtained by adding all other capacitances of the floating diffusion to the capacitance of the second capacitive element. a photoelectric conversion region configured to generate a photoelectric charge; a sense node, wherein the sense node is connected to the photoelectric conversion region, includes a first capacitive element, that has a larger capacitance than other capacitances in the sense node such that the capacitance of the first capacitive element is the dominant capacitance of the sense node, and holds the photoelectric charge generated by the photoelectric conversion region; a floating diffusion that includes a second capacitive element, that has a larger capacitance than other capacitances in the floating diffusion such that the capacitance of the second capacitive element is the dominant capacitance of the floating diffusion, and is configured to hold the photoelectric charge transferred from the sense node; a first transistor between the sense node and the floating diffusion, wherein the first transistor is configured to selectively connect the sense node to the floating diffusion to transfer the photoelectric charge held in the sense node to the floating diffusion; and a second transistor between the floating diffusion and a signal line, wherein the second transistor is configured to selectively cause a pixel signal of a voltage value corresponding to a charge amount of the photoelectric charge held in the floating diffusion to appear on the signal line, wherein the capacitance of the first capacitive element and the capacitance of the second capacitive element are provided so that a first value obtained by adding all other capacitances of the sense node to the capacitance of the first capacitive element matches a second value obtained by adding all other capacitances of the floating diffusion to the capacitance of the second capacitive element.