In a masking system a robot performs first conveyance work of making an object gripping unit grip an object and set the object at a predetermined position based on positional information of the object which was detected by a first detection unit, coating work of making a coating unit coat an adhesive on a masking location of the object which is set at the predetermined position, and second conveyance work of making a masking piece gripping unit adhere a masking piece to the masking location of the object based on positional information of the masking piece which was detected by a second detection unit.