To suppress length of the slice of a shield plate disposed in the direction of a channel, simply fix the shield plate in the direction of the slice and control the length of a detector in the direction of the slice in the detector for an X-ray CT device.

A collimator part constituted of a support plate 1, 2 and a shield plate 4 is manufactured by means of a prescribe jig. A pair of the collimator parts are connected. The support plate 1 of each collimator part is directed outside, the support plate 2 is directed inside, a pair of the collimator parts are laterally symmetrically arranged by making a lower side of a part in which the support plate 1 is protruded from the shield plate 4 and a shield plate 7 in the direction of the slice is sandwiched therebetween, and adhere thereto to be fixed. A scintillator 8 and a PDA (Photo-diode Array) substrate 9 are disposed so that they coincide with the X-ray opening part of the collimator part constituted of 2 rows.