A reinforcement member is provided and includes a reinforcement unit that has a pair of reinforcement unit bodies. Each of the reinforcement unit bodies has a protruding surface protruding from a middle part of the reinforcement unit body relative to a longitudinal direction of the reinforcement unit body. The protruding surfaces of the reinforcement unit bodies are in contact with each other while opposing each other, and opposite end parts of the reinforcement unit have rectangular cross sections when cutting the reinforcement unit perpendicularly to a longitudinal direction of the reinforcement unit. A plurality of reinforcement units are arranged and the cross sections of the opposite end parts of the reinforcement units form columns and rows of the reinforcement member.