A photoelectric sensor amplifies a received light intensity signal generated through light projection processing and light receiving processing, and performs detection processing using the amplified received light intensity signal. The photoelectric sensor is provided with a variable resistor that generates an adjustment command signal that changes linearly with respect to sensitivity adjustment manipulations performed by a user. Further, the sensor is provided with an amplifier including a variable gain amplifier configured such that the aforementioned adjustment command signal is inputted thereto. Further, the variable gain amplifier is adapted to convert the signal into a gain control signal that changes exponentially with respect to sensitivity adjustment manipulations and, further, is adapted to perform amplification processing using a gain according to the gain control signal.