The object of this invention is to decrease a stress to accumulate in a resin layer while preventing any uncured portion from forming in a side surface of the resin layer. In order to achieve this object, this invention provides a composite element manufacturing method of forming, on a surface of a base material, a resin layer to which the shape of a molding surface of a mold is transferred, thus manufacturing a composite element in which the base material and the resin layer are integrated. The resin layer is released from the mold when the resin layer is in a cured state where a viscosity Log null of a resin that forms the resin layer is 10 to 15 nulldPa.snull.