An optical unit (100) includes a light-emitting portion (10) that irradiates an analysis target with light, light-receiving portions (20) that receive light that has been reflected or diffused by the analysis target, a mounting substrate (30) on which these portions are mounted, and a plate-shaped member (40) having optical transparency. The plate-shaped member (40) is arranged so as to cover the light-emitting portion (10) and the light-receiving portions (20) that are mounted on the mounting substrate (30). Positions of the light-emitting portion (10), the light-receiving portions (20), and the plate-shaped member (40) are set such that, in the case where the analysis target is in contact with the plate-shaped member (40), light emitted from the light-emitting portion (10) is incident on two or more of the light-receiving portions (20) after being reflected or diffused by the analysis target.
