To provide a methacrylic material having excellent heat resistance without causing cracks in the surface even in the service environment at ≥200°C.

A resin composition comprises (A) 30-60 pts.wt. monomeric mixture containing a monofunctional unsaturated monomer having methyl methacrylate as the major component and a polyfunctional unsaturated monomer having at least two radically polymerizable double bonds in the molecule, (B) 40-70 pts.wt. particles of a resin which is composed of a polymer of an unsaturated monomer having methyl methacrylate as the major component and has been partially crosslinked, (C) a radical polymerization initiator, and (D) a hindered phenolic compound having at least one tertiary butyl group in the ortho-position of the phenolic hydroxyl group.