A resin composition has high flame retardancy and excellent heat resistance, peel strength with copper foil, thermal expansion coefficient, heat resistance property upon moisture absorption, and electrical properties, a prepreg and single-layer or laminated sheet, a metal foil-clad laminate using the prepreg, and the like. The resin composition has polyphenylene ether (A) having a number average molecular weight of 500 to 5000, a phosphorus-containing cyanate ester compound (B) represented by formula (13), a cyclophosphazene compound (C), a halogen-free epoxy resin (D), a cyanate ester compound (E) other than the phosphorus-containing cyanate ester compound (B), an oligomer (F) of styrene and/or substituted styrene, and a filler (G), wherein a content of the phosphorus-containing cyanate ester compound (B) is 1 to 10 parts by mass based on 100 parts by mass of a total of the (A) to (F) components.
wherein m represents an integer of 1 to 3.