To improve workability and a function by sticking a waterproof moisture permeable sheet passing no waterdrop and passing moisture to at least one surface of a synthetic resin foaming body.

A heat insulating panel 1 is constituted by adhering a waterproof moisture permeable sheet to both surfaces of a rectangular solid-shaped synthetic resin foaming body so that damage at walking time on the panel is prevented by setting compressive strength of the foaming body not less than about 5 kg gf/cm2. Next, a slip at walking time on the panel is prevented by arranging a fine recess/ projection on the waterproof moisture permeable sheet on one side of the panel 1. Then, a part of the waterproof moisture permeable sheet is projected to the outside of the foaming body to be adhered in layers to an adjacent panel 1 at execution work. For example, at execution work of a roof, after fixing the panel to a sheathing roof board 14 or the like by a nail or the like by pressing down the panel 1 arranged on asphalt roofing 15 by a sash bar 16, a roof tile 17 is arranged on the panel 1 to be installed on the sash bar 16 by a nail. Therefore, since the foaming body and the waterproof moisture perameable sheet can be simultaneously executed, rainwater can be discharged outside as steam even if rainwater infiltrates into the sheathing roof board.