There is provided a manufacturing method including: forming a molded body element with a molding material containing a ceramic powder and a binder; forming a ceramic molded body by disposing at least one molded body element in a mold and then injecting a molding material containing a ceramic powder and a binder into the mold and graft molding a graft molded body element to the molded body element; and forming a ceramic sintered body by degreasing and sintering the ceramic molded body. A graft connecting surface of the molded body element to which the graft molded body element is graft molded is formed so as to have a surface roughness of 2 μm or more in terms of Ra.