An optical measuring apparatus comprising at least one light emitting unit, a stage, at least one lens, and at least one light detector is provided. The light emitting unit emits a light beam. The stage contains accommodating spaces. The accommodating spaces move to the transmission path of the light beam in turn. The lens is located between the light emitting unit and the stage, whose orthogonal projection on the stage appears substantially to be a polygon. When one of the accommodating spaces moves to the transmission path of the light beam, a perpendicular bisector half line of each side of the polygon is not overlapped with another adjacent accommodating space of the accommodating spaces. An optical measuring method is also provided.