PURPOSE: To manufacture the titled block quickly and inexpensively by dividing a cleavage single crystal into a plurality of single-crystal scintillator elements along the cleavege planes thereof, by arranging these elements in the sequence of cleavage so that the cleavage planes face each other, and by interposing light-interrupting members between the adjacent two of a plurality of single-crystal scintillator elements respectively.

CONSTITUTION: The edge 4 of a cutting member is touched on the upper surface of a single crystal 5 for a scintillator in parallel to the cleavage plane ABCD of the crystal, and thereby the crystal is divided into scintillator elements 6 in the prescribed width Wb. Next, these scintillator elements are arranged on the same plane in a line according to the sequence of the cleavage so that the cleavage planes face each other in parallel. Then, collimators 7 are interposed between the adjacent two of the scintillator elements thus arranged, respectively, and the whole of the arranged scintillator elements 6 is pressed from the direction of the arrangement and the vertical and horizontal directions perpendicular to said direction. Using a multi-channel type scintillator element body 8 thus prepared and a multi-channel type photodiode 10, the light output planes of the scintillator elements 6 are bonded monolithically to light-receiving elements 12, and thereby a radiation detector block is obtained.