An insulation box unit and a refrigerator of the present invention employs i) rigid urethane foam with a 8.0 MPa-or-greater bending modulus, and a 60 kg/m.sup.3-or-lower density, and ii) a vacuum insulation material. The proper bending modulus provides the insulation box unit with a substantial strength, even in the case that the coverage of the vacuum insulation material with respect to the surface of the outer box exceeds 40%. The proper density prevents the insulation box unit from poor insulation efficiency due to undesired solid thermal conductivity. Despite of an extended use of the vacuum insulation material, the insulation box unit offers an excellent insulation efficiency and therefore accelerates energy saving. According to the recycling method of the present invention, rigid urethane foam formed of tolylene di-isocyanate composition, which was separated from refrigerator wastes, is recycled as a material of rigid urethane foam.