A welding torch includes: a contact tip having, on a distal-end inner circumferential surface thereof, a power supply portion that contacts a fed welding wire to supply current; and a wire guide that is provided having a predetermined clearance within the contact tip and guides the fed welding wire, and wherein the arc-welding torch is configured such that axes of the contact tip and the wire guide are relatively changed so as to cause the welding wire fed while guided by the wire guide to contact the power supply portion of the contact tip. The power supply portion of the contact tip is formed to have an axial length with which a welding current can be maintained at least a predetermined lower limit current despite a shift of a power supply point in accordance with wear of the power supply portion, more specifically, formed to have a length of 1 to 4 mm.