An object information acquiring apparatus, comprises a light irradiation unit that irradiates light onto an object and can change an emission direction of the light a scanning mechanism that moves the light irradiation unit along a first axis a probe that receives an acoustic wave generated by light irradiated onto the object a processing unit that generates characteristic information inside the object based on the acoustic wave received by the probe and a control unit that controls a position of the light irradiation unit on the first axis, and the emission direction of the light emitted from the light irradiation unit, wherein the control unit determines the emission direction of the light emitted from the light irradiation unit based on the position of the light irradiation unit on the first axis.
