An object information acquiring apparatus is used. This apparatus comprises: a light source configured to emit pulsed light of a plurality of wavelengths； a wavelength controller configured to switch the wavelength； a probe configured to receive an acoustic wave generated and propagated in an object subjected to the pulsed light emitted onto the object； a scan controller configured to move the probe within a predetermined scanning range； and an information processor configured to acquire information about the object by using a plurality of electric signals corresponding to the wavelengths of the pulsed light output from the probe at each reception position in the scanning area. The wavelength controller switches the wavelength of the pulsed light before the probe scans the entire scanning area while receiving at each reception position an acoustic wave corresponding to at least one of the wavelengths of the pulsed light.
