PURPOSE: To improve the straightness of a steel after cold drawing and straightening and to eliminate its restraightening and terstraightening by adding Al and Ti to a steel for structural use having a specified compsn. and reducing [N] as solid soln.

CONSTITUTION: This steel for machine structural use has a compsn. contg., by weight, 0.1 to 0.5% C, ≤1.0% Si, ≤2.0% Mn, 0.03 to 0.06% SolAl and/or 0.015 to 0.050% Ti, in which total N is regulated to ≤0.015 and [N] as solid soln. is regulated to ≤0.002 and the balance Fe. At the time of manufacturing parts by machining, [N] as solid soln. is regulated because the higher the bending residual amt. of wire rod recoiled from a coil after cold drawing and straightening before machining the higher its content. As for Al, it is required by the lower limit or above because it fixes N as AlN and regulates [N] as solid soln. to the above value, but in the case of more than the upper limit, it damages the cleanliness of the steel. As for N, it is regulated to prevent the formation of abundant AlN and the deterioration in its fatigue strength thereby. Furthermore, Pb is preferably regulated to ≤0.0050.