According to a method for producing a radiation detection unit, in a first step, a side portion of a first radiation detection module and a first protrusion are abutted. In a second step, a second radiation detection module is arranged within a region from which the first protrusion has been removed, and a side portion of the second radiation detection module and a second protrusion are abutted, after the first step. In a third step, each of the mounting portion of the first radiation detection module and the mounting portion of the second radiation detection module is arranged opposing a frame while spaced apart from the frame, and each of the first radiation detection module and the second radiation detection module is mounted on the frame.
