There is provided a received data processing apparatus of photoacoustic tomography including a minimum constitution unit data composition unit that sequentially reads receiving digital signals from first storage units and composes minimum constitution unit data of the acoustic wave of the minimum constitution units by performing a delay-and-sum processing. A second storage unit stores the minimum constitution unit data of the entire region of the specimen, and an image construction unit constructs an image of the specimen based on the minimum constitution unit data stored in the second storage unit. A control unit sequentially stores the minimum constitution unit data calculated by the minimum constitution unit data composition unit in the second storage unit and reads the stored minimum constitution unit data of the entire region of the specimen to transmit the minimum constitution unit data to the image construction unit.