An object information acquiring apparatus is used which has an irradiating unit irradiating an object with light with a first wavelength at a first irradiation frequency, an element receiving an acoustic wave generated by the object irradiated with the light to output an electric signal, a processing unit acquiring characteristic information on the object using the electric signal, a scanning unit changing position of the irradiating unit relative to the object, and a controlling unit controlling movement of the scanning unit. The controlling unit controls the scanning unit such that an amount of light to which an identical area of the object is exposed is larger than a smallest value of a maximum permissible exposure at the first irradiation frequency.
