PURPOSE: To prevent any defective factor such as foreign matters in a pipe, automate a coating operation and achieve labor saving and energy saving by dividing a funnel into a range from the neck junction on an inner wall to a circular cross-sectional portion and a range from the circular cross-sectional portion to a sealed portion having a short cross-section, and coating conductive graphite film thereon.

CONSTITUTION: In a device for sticking graphite on the inner surface of a funnel 4 having a circular cross-section, three band-like coating sponges 19 are stuck, at equal intervals, to a coating holder 18 having almost the same peripheral shape as that of a coated region on the inner surface of the funnel 4. When the coating sponges 19 are brought into contact with the inner surface of the funnel, a coating operation is executed. In a coating device for sticking graphite onto the short portion of the inner surface of the funnel 4, a coating sponge 28 is moved toward a tank 31 so as to be abutted against the upper portion of a shaker 30, thus impregnating graphite. Upon completion of positioning of funnel and supplying of graphite, a robot 26 starts a coating operation. Therefore, peeling of graphite can be prevented and the coating operation can be automated, thereby achieving labor saving and energy saving.