The supply of large-diameter sugi logs is expanding with the increasing ratio of the aged-class planted forest area in Japan. The purpose of this study was to improve productivity of dimension lumber from the large-diameter sugi logs. Eight sugi logs, 36 or 38 cm in diameter and 5 m in length were used. Four of the logs were cut to 2.5 m in length. Five or six wide lumbers were sawn from each log. Half of the wide lumbers sawn from each log were kiln-dried, and the other half of wide limbers were kiln-dried after being sawn into half-widths. The process of ripping wide lumbers into half-width before drying, and the process of ripping them into half-width after drying, were compared from the view point of the tendency of bow and crook. There was little difference in bow between the lumbers from two processes. It was found that the process of ripping after drying resulted in smaller crook in lumber. In the case of the 5 m length, some lumber might not meet target size because of larger bow and crook.