A radiation detection device 80 according to an embodiment of the present invention is a radiation detection device for a foreign substance inspection using a subtraction method, and includes a first radiation detector 32 that detects radiation in the first energy range transmitted through a specimen; and a second radiation detector that detects radiation in the second energy range higher than the radiation in the first energy range, and the thickness of a first scintillator layer 322 of the first radiation detector 32 is smaller than the thickness of a second scintillator layer 422 of the second radiation detector 42, and a first area S1 of each pixel 326 in a first pixel section 324 of the first radiation detector 32 is smaller than a second area S2 of each pixel 426 in a second pixel section 424 of the second radiation detector 42.