Abstract: It is unnecessary to carry out the grinding process for improving the accuracy in the inner surface configurations, dimensions and the like of the hoses around the portion to be connected to a mating member. Further, the flashes, resulting from the material leakage, are inhibited from producing during the injection molding of a connecting portion following the blow molding of a hose body. Accordingly, it is possible to obviate the deflashing and finishing process and to prevent the material shrinkage from occurring.After forming a hose body 12 with a thermoplastic resin by blow molding, the hose body 12 is set in an injection molding mold 20 including an inner mold 24 and an outer mold 22, and the inner mold 24 is adhered to the opening portion of the hose body 12 by sealing means 28, 30, 40 or 42 in a fluid-proof manner.