A carbon fiber product according to the present invention is a carbon fiber product in which one to several hundreds of hexagonal carbon layers in the shape of a bottomless cup are stacked. Edges of the hexagonal carbon layers are exposed on at least part of an outer surface or inner surface. The exposed part of the edges of the hexagonal carbon layers have a high degree of activity and excel in adhesion to base materials such as resins. Therefore, this carbon fiber product is suitable as a material for composites.