For the purpose of studying the change of mechanical properties of weld parts, shielded metal arc welding, one-pole and two-pole submerged arc welding were accomplished weldability on 60㎏/㎟ quenched and tempered high strength steel. Charpy impact values of the weld metal in welded parts by SMAW and SAW were lower than those of the heat affected zone and increased in order of bond, coarsened, refined and carbon spheroidized regions in the heat affected zone. Grain size of prior austenite or M-A constituent did not significantly affect toughness of welded parts, but precipitated carbide films which forms at the grain boundaries or within matrix and volume fraction of pearilte were most important factor for toughness.