A coating system for forming a protective layer includes first through fourth robots which are controlled by a controller and are provided close to a transport line, and sprayer mechanisms provided on ends of arms of the first through fourth robots. The motions of first through fourth robots are taught. Liquid material including an acrylic copolymer is sprayed onto an object such as a vehicle body, and dried to form a peelable protective layer on the object. The liquid material is sprayed from a first through fifth sprayers of the sprayer mechanism after the vehicle body is painted. At this time, the liquid material from the first sprayer is distributed locally in the smallest area. The area where liquid material is sprayed becomes wide gradually, in the order of the third sprayer, the fourth sprayer, the fifth sprayer, and the second sprayer. Such sprayers are also arranged in this order from an edge of the vehicle body.