A robot hand according to embodiments includes a holding unit, a bottom end, an optical sensor, and a reflecting member. The holding unit holds a thin-plate-shaped workpiece. In the bottom end, its leading part is coupled to the holding unit and its tail part is rotatably coupled to an arm. The optical sensor is provided in the bottom end and has a projector and a photoreceiver. The reflecting member is provided in the holding unit. The reflecting member reflects light from the projector, makes it pass through the holding area of the workpiece, and makes it reach the photoreceiver to form an optical path.