A coating system (10) for forming a protective layer includes a roller mechanism (34) provided at an end of an arm (46) of a robot (16a) as an end effector. The roller mechanism (34) has a roller (48), a holder (86) for supporting the roller (48), and a pipe (112). The holder (86) is removably attached to the roller (48). The pipe (112) supports the roller (48) in a freely rotating manner, and delivers the protective layer forming material to the roller (48).