A photon counting type X-ray computed tomography apparatus includes an X-ray tube, a detector, a raw data generating section, an information compression section, and a data transmission section. The X-ray tube is configured to irradiate an X-ray. The detector is configured to count photons derived from the irradiated X-ray. The raw data generating section is configured to collect results of counting performed by the detector and to generate, from the results of counting, raw data for each of a plurality of energy bands. The information compression section is configured to compare values of the raw data between the raw data generated respectively for the energy bands, and to perform information compression of each of the raw data. The data transmission section is configured to transmit the raw data compressed by the information compression.
