To achieve easy coating of a base sealant to a surrounding of a projection or the like with uniform quality in composite materials.

A sealant coating brush comprises: a support part opening toward a first direction and having a hole which is a ring shape in a planar shape vertically to the first direction; and a brush implanted on a side face facing toward the first direction around the hole. The sealant is supplied to such brush and by rotating the brush eccentrically the projection serving as a center so that an inner peripheral face of the hole contacts to the projection of a surface of a workpiece, thereby the sealant can be coated to a circular area around the projection.