PURPOSE: To prevent a deficiency in coating and uneven coating by performing coating through an endless belt as a substitute for a coating roll, and thus prolonging the time when the can bottom circumference of a seamless can body is in contact with a paint.

CONSTITUTION: A can body A is a seamless can body consisting of a can cylinder 1 and a can bottom 2 united with the can cylinder 1; the circumference part 4 of the can body 2 when viewed sectionally including a can cylinder axis is shaped in an arc and projects out of the center part 3 of the can bottom in such a way that its most projecting point 5 is the lowermost point of the can body. The can body A is moved in a conveyance direction Z by a chain conveyor 20 for can body conveyance. When the can body A reaches the place where an endless belt 40 carrying a paint and a conveyor 20 are extended in parallel, the can bottom circumferential part 4 of the can body A comes into contact with the belt 40 to be coated.