In order to generate a two-dimensional image of a sample in a short time using THz waves, provided is a reflective imaging device including a sample holder, a THz wave light source, a THz wave camera, a rotation mechanism for rotating the holder and the camera, and a processing unit. A sample unit includes an incidence member, a sample, and a reflection member. The sample includes a first region of only a membrane and a second region including a biopolymer. The camera detects, with regard to respective incident angles, a THz wave in which interference occurs between a component reflected at an interface between the incidence member and the sample and a component reflected at an interface between the sample and the reflection member, of each portion of the sample unit, and outputs a signal. The processing unit specifies an incident angle at which a signal of a first THz wave that interferes in the first region is relatively small and a signal of a second THz that interferes in the second region is relatively large, and generates a two-dimensional image of the sample based on the signal from the camera with regard to the specified incident angle.