the present invention provides a thermosetting resin composition comprising a prepolymer of a poly - p - hydroxystyrene derivative represented by the general formula ## str1 ## wherein a is a halogen group , r 1 is an alkenyl or alkenoyl group of 2 to 4 carbon atoms , 4 carbon atoms , m denotes a number of 1 to 4 and n denotes a number of 1 to 100 , an epoxy - modified polybutadiene , and an aromatic maleimide compound , and a prepreg and a laminated sheet which use said resin composition .