A method for producing a radiation detection unit for a CT device, the radiation detection unit comprising a first radiation detection module and a second radiation detection module, each module configured to detect radiation, and a frame configured to support each of the first radiation detection module and the second radiation detection module, wherein each of the first radiation detection module and the second radiation detection module includes an incident surface on which radiation is incident, a mounting portion located on an opposite side of the incident surface, and a side portion exposed in a direction orthogonal to a normal of the incident surface, the method for producing the radiation detection unit being implemented by using a jig including a reference surface, a first protrusion protruding from the reference surface, and a second protrusion protruding from the reference surface, the first protrusion being removable from the jig, the method for producing the radiation detection unit comprising: a first step of abutting the incident surface of the first radiation detection module and the reference surface of the jig so as to position the first radiation detection module; a second step of abutting the incident surface of the second radiation detection module and the reference surface of the jig so as to position the second radiation detection module; and a third step of mounting each of the first radiation detection module and the second radiation detection module on the frame, wherein, in the first step, the side portion of the first radiation detection module and the first protrusion are abutted, in the second step, the second radiation detection module is arranged within a region from which the first protrusion has been removed and the side portion of the second radiation detection module and the second protrusion are abutted, after the first step, and in the 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 the 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. a first step of abutting the incident surface of the first radiation detection module and the reference surface of the jig so as to position the first radiation detection module; a second step of abutting the incident surface of the second radiation detection module and the reference surface of the jig so as to position the second radiation detection module; and a third step of mounting each of the first radiation detection module and the second radiation detection module on the frame, wherein, in the first step, the side portion of the first radiation detection module and the first protrusion are abutted, in the second step, the second radiation detection module is arranged within a region from which the first protrusion has been removed and the side portion of the second radiation detection module and the second protrusion are abutted, after the first step, and in the 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 the 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.