With the object of realizing an X-ray CT apparatus which performs a plurality of pieces of imaging small in resolution degradation too simultaneously while suppressing an expansion of a data acquisition section that receives an electric signal of an X-ray detector, such an array that X-ray detectors in a channel direction are operated with the two as one pair is made by first detector switching means of a switching unit. This array moved by one X-ray detector in the channel direction is alternately repeated in the row or channel direction. Therefore, even when the number of receivers is small, data extending over a wide imaging range can simultaneously be collected while the degradation of resolution is being suppressed to a minor degree. By extension, imaging more coincident with an operator-aimed image can be done by making the switching use of imaging in high resolution.