To obtain an absorption distribution from a detected signal with a practical device. Light is applied to a subject, and a photoacoustic signal generated in the subjectA photoacoustic is detected. From the detected photoacoustic signal, a light differential waveform, which is a differential waveform of a temporal waveform of the light applied to the subject, is deconvolved. As a result of this deconvolution, an absorption distribution is obtained.