Thermosetting resin composition

A thermosetting resin composition comprising (A) a polyalkenylphenol resin and (B) an aromatic polymaleimide compound, wherein the polyalkenylphenol resin (A) has in the molecule at least one each of (a1) an aromatic ring unit with an alkyl-etherified phenolic hydroxyl group and with or without a 2-alkenyl group bonded thereto, and (a2) an aromatic ring unit with a phenolic hydroxyl group and with or without a 2-alkenyl group bonded thereto, at least some of the aromatic ring units (a1) and/or (a2) having a 2-alkenyl group, each aromatic ring unit being bonded by a linking group, wherein the ratio of n to (m+n) is 15 to 50% where m is the number of aromatic ring units of (a1) and n is the number of aromatic ring units of (a2), and wherein the thermosetting resin composition comprises the polyalkenylphenol resin (A) in an amount such that the proportion of 2-alkenyl groups is 0.4 to 1.5 mol relative to 1 mol of maleimide groups in the aromatic polymaleimide compound (B) wherein the cured product of the thermosetting composition has a water absorption rate of less than or equal to 0.3%.