The objectives of this study are to clarify the wood properties of Sanbu-sugi cultivar of sugi (Cryptomeria japonica D. Don) planted in Chiba prefecture, Japan. Stress-wave velocity (SWV) of stem, dynamic Young's modulus (DMOE) of logs, wood properties (basic density, latewood tracheid length, microfibril angle of S2 layer in latewood tracheid, and static bending properties), and bending properties of 2 by 4's were investigated for Sanbu-sugi cultivar with different 5 stand ages (11, 19, 30,

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... and 70-years-old). From obtained results, changes of wood properties due to changes of stand age were also discussed. Based on the radial variation of wood properties, juvenile wood of Sanbu-sugi existed from pith to 15th or 20th annual ring from pith. SWV of stem and DMOE of logs increased with increase of stand age up to 30 years, and then it slightly decreased. Thus, SWV of stem and DMOE of logs became stable from about 30-years-old due to increase of mature wood volume. Mean values of modulus of elasticity and modulus of rupture in 2 by 4's were 8.54 GPa and 56.2 MPa, respectively. Modulus of elasticity of 2 by 4's in mature wood was almost the same for that obtained from trees with different stand age.