A photoelectric converting apparatus of the present invention includes, in one embodiment, a photoelectric converting element, a resetting transistor in which a source is connected to the photoelectric converting element and a drain is connected to a resetting power source, a readout transistor in which a gate is connected to the photoelectric converting element and a drain is connected to a readout power source, a signal line connected to a source of the readout transistor, a selecting transistor connected between the readout power source or the signal line and the readout transistor, and a constant current source connected to the signal line.