The present disclosure provides a gamma ray imaging device and an imaging method, where the imaging device includes a plurality of separate detectors. The plurality of separate detectors are provided at an appropriate spatial position, in an appropriate arrangement manner and are of an appropriate detector material, such that when rays emitted from different positions in an imaging area reach at least one of the plurality of separate detectors, at least one of the thicknesses of the detectors, the materials of the detectors, and the numbers of the detectors though which the rays pass are different, thereby achieving the effect of determining the directions of rays.