PURPOSE: To efficiently obtain a titled heat insulator by blow molding a hollow sheath, and then filling foamable resin liquid from the blowing point or another filling port of a blowing mold, thereby continuously performing the molding of a hollow sheath and the molding of a foamable layer.

CONSTITUTION: Thermoplastic resin sheet 10 such as ABS resin or the like is, for example, blow-molded in the molding space 11 between lower and upper molds 1 and 2, thereby obtaining a hollow molded unit. Foamable resin liquid 7 such as foamable urethane stock liquid is filled, for example, in the space 11 through a compressed air passes without removing the unit, thereby obtaining the desired laminated heat insulator 13.