To provide a heat insulating material which exerts a sufficient heat insulating effect while limiting arrangement thickness in construction to the order of a few millimeters.

In this heat insulating material, a resin emulsion and a hollow resin material are blended into a main material mainly composed of calcium oxide. Otherwise, the heat insulating material, in which the resin emulsion and the hollow resin material are blended into a main material mainly composed of sand and water glass, is molded like a roll. Additionally, a hollow acrylic resin material is used as the hollow resin material, and a compounding ratio of the hollow resin material is set at 20 wt.%.