A photoacoustic diagnostic apparatus having a light source, a probe which receives an acoustic wave generated when light is directed onto an object from a light source and which converts the acoustic wave into an electrical signal, a memory unit which records the electrical signal and a memory control unit which controls whether or not to cause the memory unit to record the electrical signal. The memory control unit controls the memory unit on the basis of a timing at which the probe receives an acoustic wave generated from a portion other than a light absorbing material inside an object.