Abstract: A process for producing an ERW tube having welds which have been improved in toughness without adversely affecting the toughness of the parent metal of the tube is disclosed. The process comprises forming a continuous low alloy steel strip into a tubular shape through a series of forming rolls, continuously carrying out electrical resistance welding of a seam which is formed from the opposite side edges of the hoop and which extends in the longitudinal direction to produce an electrical resistance welded tube, heating the welds of the thus obtained electrical seam welded tube to a temperature not lower than the A.sub.c3 point, then cooling the heated welds at cooling rate of 15.degree.-30.degree. C./sec for at least between 800.degree. C. and the A.sub.r1 point, and tempering the thus cooled welds of the tube at a temperature of 450.degree.-800.degree. C.