1. A radiological imaging apparatus, comprising: an X-ray source which is moved around a bed for supporting a test subject; and a radiation detecting device having a γ-ray detecting section for outputting detection signal of γ-rays, and an X-ray detecting section for outputting detection signal of X-rays wherein at least part of said X-ray detecting section is positioned in a region formed between one end and the other end of said γ-ray detecting section in the longitudinal direction of said bed.