Abstract: A method of welding corner joints by means of a multiple electrode submerged-arc welding and adapted to be utilized for the manufacture of a hollow square steel pillar and the like structural frameworks is disclosed. The method of welding is effected under the following three conditions:1. The distance between first and second electrodes is 30 to 80 mm,2. The current flowing through the second electrode is 60 to 85% of the current flowing through the first electrode, and3. The welding heat input H is given byH .ltoreq. 24d.t KJoule/cmwhere t is a thickness of a steel flange plate in cm and d is a required penetration depth in cm, whereby a weld bead is completed by a single pass of welding.