A method of making a casting having a cast portion and a cap nut includes forming a hole with a stepped shape in the cap nut to have a large-diameter hole on an opening side and a threaded small-diameter hole on a bottom side, inserting a fixing member into the large-diameter hole, supporting the fixing member in a sand mold, pouring a casting material into the sand mold so that the cap nut is enveloped in the cast portion and that a first surface of the cap nut adjacent to the hole is exposed outside without being covered with a second surface of the cast portion, and removing the fixing member from the cap nut after the casting is taken out of the sand mold.