An imaging unit (5, 105) that images a subject having an unevenness pattern on a surface, the imaging unit comprising: a surface light source (50, 150) that emits with a constant output illumination light illuminating the surface of the subject; an imager (51, 151) that receives reflected light reflected by the surface of the subject; and a beam splitter that is arranged at a location at which the illumination light emitted from the surface light source and the reflected light incident on the imager intersect with each other, wherein: the illumination light emitted from the surface light source is incident on the surface of the subject via the beam splitter; the reflected light reflected by the surface of the subject is incident on the imager via the beam splitter; and the illumination light incident on the surface of the subject includes parallel light that is perpendicularly incident on the surface of the subject, and diffused light, characterized in that the surface light source (50, 150) includes: a light source element that emits light; a light guide plate that has, on a lower surface thereof, a prism pattern reflecting the light emitted from the light source element, light guide plate emitting, from an upper surface thereof, the light reflected by the prism pattern; and a diffusion film that is layered on the upper surface of the light guide plate, and disperses a portion of the light emitted from the upper surface to generate the parallel light and the diffused light. a surface light source (50, 150) that emits with a constant output illumination light illuminating the surface of the subject; an imager (51, 151) that receives reflected light reflected by the surface of the subject; and a beam splitter that is arranged at a location at which the illumination light emitted from the surface light source and the reflected light incident on the imager intersect with each other, wherein: the illumination light emitted from the surface light source is incident on the surface of the subject via the beam splitter; the reflected light reflected by the surface of the subject is incident on the imager via the beam splitter; and the illumination light incident on the surface of the subject includes parallel light that is perpendicularly incident on the surface of the subject, and diffused light, characterized in that the surface light source (50, 150) includes: a light source element that emits light; a light guide plate that has, on a lower surface thereof, a prism pattern reflecting the light emitted from the light source element, light guide plate emitting, from an upper surface thereof, the light reflected by the prism pattern; and a diffusion film that is layered on the upper surface of the light guide plate, and disperses a portion of the light emitted from the upper surface to generate the parallel light and the diffused light. the illumination light emitted from the surface light source is incident on the surface of the subject via the beam splitter; the reflected light reflected by the surface of the subject is incident on the imager via the beam splitter; and the illumination light incident on the surface of the subject includes parallel light that is perpendicularly incident on the surface of the subject, and diffused light, characterized in that the surface light source (50, 150) includes: a light source element that emits light; a light guide plate that has, on a lower surface thereof, a prism pattern reflecting the light emitted from the light source element, light guide plate emitting, from an upper surface thereof, the light reflected by the prism pattern; and a diffusion film that is layered on the upper surface of the light guide plate, and disperses a portion of the light emitted from the upper surface to generate the parallel light and the diffused light.