A reformer includes a burner that generates thermal energy, and a reforming reaction unit that is supplied with thermal energy from the burner to generate a hydrogen-rich gas from a fuel, wherein the burner includes a burner main body having first and second portions that are constructed by bending the burner main body to form bended portions and coupling the bended portions together, wherein the burner main body is disposed in an inner portion of the reforming reaction unit, and wherein a first catalyst is filled in an inner portion of the burner main body.