A composite preform including a preform and a plastic member in close contact with the outer surface of the preform is made by preparing the preform made of plastic material and arranging the plastic member to surround the outer surface of the preform. Subsequently, the composite preform is heated and inserted in a blow molding die and undergoes blow molding in the blow molding die, by which the preform and the plastic member of the composite preform are inflated integrally and a composite container is obtained.