A thermosetting resin composition includes a polyalkenyl phenol resin (A) and an aromatic polymaleimide compound (B). Polyalkenyl phenol resin (A) has at least one aromatic ring unit (a1) which may have a 2-alkenyl group bonded thereto and in which a phenolic hydroxyl group is alkyl-etherified, and at least one aromatic ring unit (a2) which has a phenolic hydroxyl group and which may have a 2-alkenyl group bonded thereto. At least one of aromatic ring units (a1, a2) has a 2-alkenyl group. Each aromatic ring unit is bonded by a linking group. When m represents the number of aromatic ring units (a1), and n represents the number of aromatic ring units (a2), n to (m+n) is 10-60%. The polyalkenyl phenol resin (A) is included in an amount at which the amount of 2-alkenyl groups becomes 0.4-1.5 mol per mol of maleimide groups in the aromatic polymaleimide compound (B).