To ensure air relief passages by the unevenness at the time of lamination and to facilitate peeling at the time of repairing, by providing unevenness on at least the single surface of a sheet base material made of a resin having flexibility.

A resin sheet is constituted by using a synthetic resin as a base resin having flexibility at a time of the molding into a sheet shape. As this base resin, a polyolefinic resin capable of applying a crosslinked structure to a base material by radiation is suitable. As this polyolefinic resin, polyethylene or an ethylene/vinyl acetate copolymer is designated. By applying emboss processing to this base material, unevenness is provided and the size of this unevenness is pref. 0.1-5.0mm square, more pref., 0.2-2.0mm square. The unevenness can be provided to the single surface or both surfaces of the base material. A Vicat softening point of the base resin constituting the sheet base material is pref. 40-130°C.