Disclosed is an optical detector in which a boundary line BY defining an edge of a semiconductor region 14 is covered with signal read wiring E3 and a capacitor is configured between the semiconductor region 14 and the signal read wiring E3. High frequency components peak components of a carrier are quickly extracted to the outside via the capacitor, but the signal read wiring E3 covers the boundary line BY so that a semiconductor potential in the vicinity of the boundary line is stabilized and an output signal is stabilized.