It is well known fact that physiological root activity of rice, i.e., α－naphthylamine oxidation, is related to the dry weight of rice plant. It indicates that the growth of rice plant might be controlled by the physiological root activity of rice. Bleeding rate is one of the indexes of physiological root activity. However, there is little information about relationship between bleeding rate and dry matter increasing rate of rice plant. The objective of this study is to clarify the relationship between bleeding rate per panicle or per top dry weight and top dry matter increasing rate. Bleeding rate per panicle or per top dry weight did not relate to CGR, NAR, and RGR. There was no relationship between bleeding rate per panicle and panicle dry matter increasing rate. But, bleeding rate per top dry weight related to panicle dry matter increasing rate at ５% level. This fact suggests that cultivation management to get high yield of rice might be supported by bleeding rate per top dry weight.　キーワード：水稲，出液速度，稲乾物加速度　Key Words : rice, bleeding rate, panicle dry matter increasing rate