First, a composite preform 70 including a preform 10a and a plastic member 40a in close contact with the outer surface of the preform 10a is made by preparing the preform 10a made of plastic material and arranging the plastic member 40a to surround the outer surface of the preform 10a. Subsequently, the composite preform 70 is heated and inserted in a blow molding die 50 and undergoes blow molding in the blow molding die 50, by which the preform 10a and the plastic member 40a of the composite preform 70 are inflated integrally and a composite container 10A is obtained.