In this report, a method to predict the fatigue strength in welded structure member of ship construction is studied considering the effects of statistical characteristics of mild steels and weld toe shapes on the fatigue crack initiation life. The fatigue test under pulsating bending load is carried out with the model specimens of the web frame in double bottom of ship hull. The propriety of the fatigue life curve with probability of failure in the transverse strength members of ship hull construction is confirmed by the comparison with the results of fatigue test on the model of the various transverse strength members.