To provide technology enhancing productivity in a vehicle body assembling facility for manufacturing a plurality of kinds of products while mixedly making them existed in one welding line.

The vehicle body assembling facility 40 includes a working area 36 provided with a welding robot 29; a jig storage area 33 for storing welding jigs; a part storage area 42 for storing a part, i.e., an object to be welded; and a part transferring mechanism 43 for transferring the part placed in the part storage area 42 to the jig placed in the working area 36, and is provided with a jig transportation conveyor 37 for transporting the jig from the jig storage area 33 to the working area 36; and an elevated frame 44 straddling the jig transportation conveyor 37 and supporting the part transferring mechanism 43.