PURPOSE: To manufacture at low cost a cold drawn low alloy steel wire for mechanical structural use for carburizing hardening which is free from abnormal dots at the time of carburizing hardening, excellent in quality with the simplified manufacturing process.

CONSTITUTION: As for the low alloy steel for machine structural use, the mean extraction temperature of the stock of cold drawn low alloy steel for machine structural use containing, by weight, 0.025-0.045% Al and 0.015-0.025% N is set to ≥1120°C and the stock temperature is kept at ≥880°C in the whole rolling process. The stock is rolled to realize the uniform solid solution diffusion of AlN in the rolled stock, and the hardness of the rolled stock is regulated to HRB75-85, and the pickling and coating treatment is achieved without annealing. The finish drawing where the section reduction ratio due to the cold drawing is 15-25% and the flaw detection test are achieved to obtain the cold drawn low alloy steel wire for mechanical structural use for carburizing hardening which is HRB90-98 in the hardness, free from abnormal dots in the carburizing hardening treatment, and excellent in the quality.