An object information acquiring apparatus includes a probe configured to detect a photoacoustic wave generated from an object irradiated with light, a signal collector configured to generate a first detection signal from the photoacoustic wave, a signal processor configured to generate, from the first detection signal, a second detection signal in which a component having a phase inverted from the phase of a component deriving from the photoacoustic wave is reduced, by using a differential signal of an impulse response of the probe, and an image generator configured to generate image data on the inside of the object using the second detection signal.