Abstract: A plastic foam material composed of a polyolefin based resin composition, consists essentially of specified amounts of polypropylene based resins and polyethylene based resins, included from about 20 to about 65 weight percent of a cross linked portion. The cross linked portion consists of from about 55 to about 95 weight percent of a cross linked polypropylene and from about 5 to about 45 weight percent of cross linked polyethylene. The amount of cross-linkage can be determined by a xylene extraction technique. The plastic foam material may further include specified amounts of a cross-linking agent and specified amounts of an organic thermodecomposition foaming agent. The thermodecomposition foaming agent decomposes at sufficiently high temperatures to yield a plastic foam material, which exhibits superior adherence properties and fewer deformities of its surface exemplified by swelling, shrinkage and wrinkling of its surface. A method to produce the plastic foam material is also disclosed.