The characteristics of Fatigue Damage Sensors (FDS) that are in use for fatigue life estimation of monitoring structural welding members in ship structures are discussed in order to improve prediction accuracy of estimated fatigue life exposed to random wave loads such as storms under various loading conditions peculiar to ship structures. In our past research, coefficients, which named load effect factors (LEFs) affected by loading histories against constant amplitude loading were introduced for the estimation procedure using FDSs and confirmed by numerical simulations and fatigue tests under simplified storm-type loading patterns or load histories based on a storm model in consideration of variable of sea areas and seasons. In this paper, we proposed the estimation method of the abovementioned LEFs using several frequency distribution data such as significant wave height and stress obtained from a storm model simulated actual sea condition.