A bell cup includes an inner surface and a coating material diffusion surface on the inner surface of the bell cup. The coating material diffusion surface includes a first range extending from an end part of the coating material diffusion surface to a center part of the coating material diffusion surface, the end part being disposed toward a proximal end of the bell cup, being a convex curved surface facing towards the rotation axis, and on which, in a cross section of any plane that includes the rotation axis, normal line components of a centrifugal force acting on a coating material liquid film due to rotation of the bell cup are substantially equal, and a second range extending from the center part to a distal end edge of the bell cup, and being a being a concave curved surface facing towards the rotation axis.