To provide blow molding technique by which the degree of freedom in equipment layout can be raised by contriving reduced cost through miniaturization of the molding apparatus.

The blow molding apparatus 10 has a cylindrical vessel 30 providing an open port 30a at an end along the direction of the axial line, a plurality of molding dies 40 which is arranged so as to come into contact with the inner peripheral surface 30b of the cylindrical vessel and on which molding recessed part 41 is formed, holding means 50 for holding a sheet-like blank material 21 on respectively a plurality of the molding dies, sealing means 60 for closing the open port and pressure supplying means 70 for supplying a gas pressure for bring the blank material into press-contact with the molding recessed parts the blank material on the forming recessed part.