To provide a composite material having excellent adhesivity to a polar polymer matrix, high mechanical properties and light weight, and provide a method for the production of the composite material.

The composite material contains an ultra-high molecular weight polyethylene fiber having a weight average molecular weight of ≥1,000,000, composed mainly of a polyethylene and treated with a diisocyanate compound after two or more physical treatments and a polar polymer matrix. The composite material has a tensile strength of ≥1.0 GPa and an elastic modulus of ≥30 GPa. The method for the production of the composite material is provided.