The generation of smoke in the molding when the mold is suppressed, and also provides a degradable shell mold and the mold strength of the resin composition for maintaining, and resin coated sand using the same phenolic resin. The resin composition for the shell mold, and a phenol resin and an aromatic condensed phosphoric acid ester. Phenol resin, is used as a binder of the resin coated sand used in the production of molds and cores for shell mold casting, etc. of such as cast iron, cast steel, aluminum. In addition, the aromatic condensed phosphoric acid ester as a disintegrator for improving the disintegration of the template after, pouring the casting is very effective.