In a photoacoustic apparatus, a light source irradiates an inspection target with pulsed light; a detector detects acoustic waves generated in the inspection target due to interaction of the pulsed light with the inspection target, and outputs detection signals corresponding to the detected acoustic waves; a light-quantity measurement unit measures the quantity of the light output from the light source; and a signal processor obtains information on an inside of the inspection target by using the detection signals output from the detector. The signal processor also corrects intensities of the detection signals so as to suppress variations in intensities of the detection signals caused by a temporal change in the quantity of the light.