Abstract: A marking device is provided that can confirm a mark imprinted on a molded piece from outside a molding tool and can inscribe a plurality of marks with a sole marker. The marking device consists of a reference sleeve, a top imprint portion, a sleeve, a top imprint portion, and a pin. The reference sleeve is fixedly assembled and has the top reference imprint surface confronting a molding area, a reference imprint mark being formed on the stamp surface. The top imprint portion is rotatably journaled within the reference sleeve and has the top display imprint surface being flush with the top reference imprint surface, on which data imprint marks to be pointed by a reference imprint mark are formed. The sleeve has a base end actuator, on which data display are indicated, formed at a protrusion protruded from a molding area outward.