To investigate the relations between growth and the wood properties of Japanese larch (Larix kaempferi), six sample trees of varied ages and radial growth were felled and the ring width, ring density, percentage of latewood, and some other factors were determined. There were significant differences in ring density and percentage of latewood between sample trees with vigorous growth and those with poor growth. In corewood the ring density decreased with increasing ring width for all sample trees, whereas in outerwood this trend did not appear. Moreover, the latewood width increased with the increment of ring width only in outerwood, whereas there was almost no change in the corewood. The variation in patterns of ring width, ring density, and percentage of latewood in the radial direction and the relation with height was also studied.