Abstract: A photometric amplifier circuit, having a photocurrent converting element connected between a pair of inverting and noninverting input terminals of a differential amplifier, for amplifying an electric signal responsive to the quantity of light, is characterized in that a differentiating circuit is connected between the inverting input terminal of the differential amplifier and a power supply to thereby prevent the differential amplifier from producing an undesired latch output when the power is supplied from the power supply, with the result that, after this power is supplied, a normal amplifying operation is capable of being obtained at an earlier time. This invention is particularly adapted for an automatic exposure control system for cameras to precisely control the exposure of the camera.