1. A commodity recognition apparatus comprising: an image sensor which has an area image sensor to photograph a commodity and generate a captured image of the commodity; a first memory configured to store an image of a hand; a second memory configured to store computer-readable instructions; and a central processing unit which processes the captured image according to the computer-readable instructions causing the commodity recognition apparatus to: recognize the commodity imaged as one object in the captured image; compare the captured image with the image of the hand and recognize a shape of a hand as another object in the captured image; specify a reason why the commodity cannot be recognized is that a shape of the commodity is almost entirely shielded by a hand of an operator when the shape of the hand is recognized in the captured image; and notify the operator of the reason specified.