An object information acquiring apparatus includes: a light source radiating first light having a first wavelength λ1 and second light having a second wavelength λ2 a detection unit detecting an acoustic wave generated from an object irradiated with the light, and converting the acoustic wave into a detection signal and a signal processing unit acquiring characteristic information of the inside of the object based on the detection signal. The signal processing unit acquires the characteristic information by performing subtraction processing between a signal generated as a result of the first light being absorbed by hemoglobin and a signal generated as a result of the second light being absorbed by hemoglobin.
