A radiation detection device for detecting a radiation transmitted through a target object conveyed in a conveyance direction, the radiation detection device comprising: a first scintillator configured to convert a radiation of a low energy range in the radiation transmitted through the target object into first scintillation light; a first line sensor having a plurality of first pixels arranged along a detection direction intersecting the conveyance direction, the first line sensor configured to detect the first scintillation light with the first pixels to output first image data; a second scintillator configured to convert a radiation of a high energy range in the radiation transmitted through the target object into second scintillation light, the high energy range being higher than the low energy range; a second line sensor having a plurality of second pixels arranged along the detection direction intersecting the conveyance direction, the second line sensor configured to detect the second scintillation light with the second pixels to output second image data; and an image processing unit including an minimum filtering process circuit configured to execute a first thinning-out process including a minimum filtering process on the first image data outputted from the first line sensor, in which the image data of the lower luminance of the signals from adjacent pixels is left, and the remaining image data is removed; and an averaging process circuit configured to execute a second thinning-out process including an averaging process or an adding process on the second image data outputted from the second line sensor, in which an average value of the luminances of the signals from adjacent pixels is calculated or luminances of signals from adjacent pixels are added together to reduce the quantity of data, wherein the first pixels of the first line sensor and the second pixels of the second line sensor are identical to each other in number and are arranged at an identical pixel pitch. a first scintillator configured to convert a radiation of a low energy range in the radiation transmitted through the target object into first scintillation light; a first line sensor having a plurality of first pixels arranged along a detection direction intersecting the conveyance direction, the first line sensor configured to detect the first scintillation light with the first pixels to output first image data; a second scintillator configured to convert a radiation of a high energy range in the radiation transmitted through the target object into second scintillation light, the high energy range being higher than the low energy range; a second line sensor having a plurality of second pixels arranged along the detection direction intersecting the conveyance direction, the second line sensor configured to detect the second scintillation light with the second pixels to output second image data; and an image processing unit including an minimum filtering process circuit configured to execute a first thinning-out process including a minimum filtering process on the first image data outputted from the first line sensor, in which the image data of the lower luminance of the signals from adjacent pixels is left, and the remaining image data is removed; and an averaging process circuit configured to execute a second thinning-out process including an averaging process or an adding process on the second image data outputted from the second line sensor, in which an average value of the luminances of the signals from adjacent pixels is calculated or luminances of signals from adjacent pixels are added together to reduce the quantity of data, an minimum filtering process circuit configured to execute a first thinning-out process including a minimum filtering process on the first image data outputted from the first line sensor, in which the image data of the lower luminance of the signals from adjacent pixels is left, and the remaining image data is removed; and an averaging process circuit configured to execute a second thinning-out process including an averaging process or an adding process on the second image data outputted from the second line sensor, in which an average value of the luminances of the signals from adjacent pixels is calculated or luminances of signals from adjacent pixels are added together to reduce the quantity of data, wherein the first pixels of the first line sensor and the second pixels of the second line sensor are identical to each other in number and are arranged at an identical pixel pitch.