PROBLEM TO BE SOLVED : To provide a low carbon unfired brick being excellent in corrosion resistance, thermal shock resistance, high high-temperature strength and slag penetration resistance and having sufficient service durability and hardly causing carbon pick-up.SOLUTION : The low carbon unfired brick is manufactured by adding a mesophase pitch of 0.5-5 mass% and a thermosetting resin of 0.5-5 mass% per total mass to a refractory raw material mixture not containing flake-like graphite of 100 mass%, kneading, forming and heating. As a carbon composite texture generated by the carbonization of the mesophase pitch and the thermosetting resin is formed to be a nano-sized fiber or a strip-like shape under their coexistence, the low carbon unfired brick being excellent in flexibility and thermal shock resistance and easily developing strength is obtained.