An object is to prevent occurrence of an insensitive zone to radiation in parallel arrangement of multiple units. This radiation detecting unit 1 is provided with a PD array 5 including a plurality of PD elements 13 arrayed opposite to a scintillator 3 and output electrode pads 23 arrayed corresponding to the PD elements 13, integrated circuits 7 for processing signals from the PD elements 13, a flexible substrate 9 for mounting of the PD array 5 and integrated circuits 7, and a radiation shield plate 1 provided opposite to the PD array 5 with the flexible substrate 9 in between and formed so that ends thereof 11a are located inside the PD array 5 the output electrode pads 23 have an array pitch made shorter than that of PD elements 13 the flexible substrate 9 is folded along the ends 11a at intermediate regions A 3 between mounting regions of the PD array 5 and integrated circuits 7, whereby the integrated circuits 7 are arranged on the opposite side to the PD elements 13 with the radiation shield plate 11 in between.
