A subject information acquisition apparatus includes receiving units that are arranged along an arc shape and configured to receive a photoacoustic wave generated in a subject in response to light from a light source and convert the photoacoustic wave into a time-series electric signal, a driving unit configured to scan the receiving units, and a processing unit configured to acquire information about an inside of the subject. The light source emits light at a certain timing. The receiving unit receives a photoacoustic wave at a correspondent timing synchronized with light emission. The driving unit causes the receiving unit to perform scanning to allow the receiving unit to receive the photoacoustic wave in a predetermined region in synchronization with the correspondent timing. The processing unit acquires the information based on positional coordinates in the region and a signal resulting from summation of time-series electric signals corresponding to the correspondent timing.
