Major requirements to low temperature service steels are the resistance to fracture initiation and crack arrestability which, naturally, are required for LPG storage tanks. Low temperature service steels are classified into Al-killed steel, 2.5% Ni steel, 3.5% Ni steel and so on. A welded joint is generally not uniform but contains partially embrittled region, which often is unignorable and makes it difficult to evaluate the toughness of welded joint. In this paper, the welded joints containing embrittled regions were prepared artificially and its influence on the fracture behavior was studied. In the three point bending COD test, the small-sized specimen showed an indication of the fracture initiation when the crack tip is located in an embrittled region. However, since the probability of finding a crack tip in the embrittled region is small and the force of restraint is large when a whole welded joint is considered, fractures by a low stress seldom occur. Even under the most unfavorable condition, there is a tendency of a multi-step fracture rather than a single-step fracture.