A polyurethane-based adhesive composition for concrete reinforcement contains a polyol component having at least two hydroxy groups per molecule and a polyisocyanate component having at least two isocyanate groups per molecule. The polyol component includes 70 mass % or more diol in 100 mass % as a total amount of the polyol component. The polyisocyanate component includes 5 mass % or more and 95 mass % or less polymethylene polyphenyl polyisocyanate in 100 mass % as a total amount of the polyisocyanate component.