To obtain a resin-reinforcing material which has excellent dimensional stability, mechanical properties and homogenity and is useful for composite materials and the like by using a specific sheath-core type conjugate fiber.

This resin-reinforcing material uses sheath-core conjugate fibers each of which comprises a sea-island component structure formed a sea component and an island component and has a smoothly undulated surface. The sea component comprises a meltable liquid crystal polyester (A polymer) comprising the repeating component units formed from an aromatic hydroxycarboxylic acid as a core component and a flexible thermoplastic polymer (B polymer) such as a polyolefin as a sea component. The island component comprises a meltable liquid-crystal polyester (C polymer). The resin-reinforcing material comprises the woven fabric of the sheath-core type conjugate fibers, has a 200-500 mesh mesh-like structure having an opening rate of ≥30%, and is preferably integrated with a resin to produce a composite material.