To provide a welding apparatus which can improve a degree of freedom in the design of a portion for holding a welding torch arranged on a carriage, and further can improve its workability.

The welding apparatus comprises the carriage 2 capable of running by itself on a carriage running plane A, a welding torch 3 mounted on the carriage 2, and a welding torch holding portion 4 for holding the welding torch 3 so as to be movable in the vertical, cross, and horizontal directions of the carriage 2. Magnets 6 are arranged on the front and rear faces of the carriage 2 so as to movably attract the carriage 2 toward the carriage running plane A in the state that the attracting planes 6a of the magnets 6 are opposed to the carriage running plane A, and also a magnet driving mechanism 7 for switching over an attracting mode, in which the attracting planes 6a of the magnets 6 are opposed to the carriage running plane A, and a releasing mode, in which the attracting planes 6a of the magnets 6 are crossing perpendicular to the carriage running plane A.