To provide a resin composition to which heat resistance is donated without extremely damaging transparence of a molded item and to provide a sheet made thereof.

A resin composition comprises 100 pts.wt. of a resin (A) which contains 15 to 50 wt.% of an oxygen atom in a molecule and has a glass transition temperature of 0 to 90°C and tanδ of 0.07 to 1 at 20°C and 0.01 to 20 pts.wt. of a swellable layer silicate (B). A sheet is made of the resin composition and is not less than 50 μm thick.