In this study, the differences of green moisture content of heartwood amoung sugi cultivars grown in a 20-year-old stand were investigated. The diameter and the green moisture content of the heartwood at the breast height were measured for fifteen to forty trees each from twelve cultivars. Five trees from each cultivars were felled, and disks, 10 cm thick, were removed from the breast height of sample trees. Hot water extractives (%) of the heartwood and water absorption from longitudinal-tangential surface were measured. 1) Green moisture content of the heartwood varied with the cultivars, and the coefficient of variation in green moisture content in a cultivar was relatively small compared to that in whole samples (Table 2). The results may mean that each cultivars have the inherent values in green moisture content of the heartwood. 2) In most of cultivars, there was significant correlation between diameter at the breast height and green moisture content of the heartwood (table 3), indicating that the differences of the growth rate amoung trees have influence on the variation in green moisture content within cultivars. 3) High correlation between hot water extractives and green moisture content of the heartwood was observed (Fig.3), therefore it was presumed that the differences amoung cultivars and the variation within cultivars in green moisture content of the heartwood were caused by the differences of hot water extractives amoung and within cultivars. 4) Hot water extractives significantly correlated with the water absorption rate of the heartwood (Fig. 4).