PURPOSE: To reduce man-hours and to shorten a lead time by suspending two welding equipments on a jib to make a couple and setting the center of a joint right under a locus circle of the mid point of suspending points of the welding equipments of the jib to carry out welding assembling.

CONSTITUTION: The welding equipments 4 suspended on a jib crane are moved close to an object to be welded by the turning of a jib 7b and the equipments having the high degree of freedom are positioned by a light and flexible hoisting accessory such as a wire by a lifting force above a balancer. Namely, when the central point of the welding position is arranged right under the locus circle 9 of a fixed point 7d of the previous point jib, the welding equipments 4 can be easily brought to the welding position by rotating the jib 7b. Consequently, the two welding equipments 4 are suspended on the one jib 7b to make a couple, at least the two welding equipments 4 are operated at the same time, several couples of these are provided and welding is performed with many equipments waiting as a principle.