It is an object of the present invention to provide a phenolic novolak resin for a shell mold which is capable of simultaneously solving a problem of gas defect caused by a tar generated at the time of casting and a problem of a casting defect represented by veining. As the phenolic novolak resin in RCS for the shell mold, there is used a copolycondensation resin-type phenolic novolak resin obtained by reacting a phenol and an alkylphenol, with at least one of aldehydes, wherein a ratio of an ortho-bond to a para-bond of a methylene group in the phenolic novolak resin is not less than 1.5, and a fire-resisitant particle is coated with this resin.