It was limited to 60/40 brass and the adjustment of grain size was performed, thereafter, it was processed by one way torsion working and back-torsion working. The effect of both workings on the work hardening and the surface roughness of 60/40 brass were investigated. The quenched material has excellent surface roughness in comparison with the furnace-cooled material both after and before workings. It seemed that a little difference in their grain size (15-55μm) affects the restoration ratio of surface roughness. For the back-torsion worked material, as the grain size is coarse, the amount of hardening increases. If the β phase ratio is more, it is easy to become hardened. Inversely, if the β phase ratio is less, it obtains the maximum amount of hardening.