An object information acquiring apparatus, comprising: a light source configured to emit pulsed light of a plurality of wavelengths including a first wavelength and a second wavelength different from the first wavelength; a wavelength controller configured to switch the wavelength of the pulsed light; a probe configured to receive a respective acoustic wave generated in an object each time that the object is irradiated with the pulsed light emitted from the light source; 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 predetermined scanning range; wherein the wavelength controller switches the wavelength of the pulsed light before the probe scans the entire scanning range while receiving at each reception position an acoustic wave corresponding to at least one of the wavelengths of the pulsed light, characterized in that the wavelength controller switches the wavelength of the pulsed light each time the pulsed light is emitted, the scanning range is divided into a plurality of partial areas in a sub-scan direction intersecting the main scan direction, wherein the main scan direction is identical to the direction of a scanning path followed when the probe is moved while receiving an acoustic wave at each of plural reception positions within each of the partial areas of the scanning range, wherein the partial areas correspond to scanning orbits followed when the probe is moved in the main scan direction, the wavelength controller is configured to switch the wavelength of the pulsed light while the probe moves in the partial areas. a light source configured to emit pulsed light of a plurality of wavelengths including a first wavelength and a second wavelength different from the first wavelength; a wavelength controller configured to switch the wavelength of the pulsed light; a probe configured to receive a respective acoustic wave generated in an object each time that the object is irradiated with the pulsed light emitted from the light source; 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 predetermined scanning range; wherein the wavelength controller switches the wavelength of the pulsed light before the probe scans the entire scanning range while receiving at each reception position an acoustic wave corresponding to at least one of the wavelengths of the pulsed light, characterized in that the wavelength controller switches the wavelength of the pulsed light each time the pulsed light is emitted, the scanning range is divided into a plurality of partial areas in a sub-scan direction intersecting the main scan direction, wherein the main scan direction is identical to the direction of a scanning path followed when the probe is moved while receiving an acoustic wave at each of plural reception positions within each of the partial areas of the scanning range, wherein the partial areas correspond to scanning orbits followed when the probe is moved in the main scan direction, the wavelength controller is configured to switch the wavelength of the pulsed light while the probe moves in the partial areas.