This study was conducted to find out the consumptive use of irrigated water for calculation of a duty of water in paddy rice. Tall statured Japonica rice variety is Jinju(late). Short statured Tongil varities-Taebaek(early) and Pungsan(medium) were planted on the experimental farm of kyungpook National University in 1983. The results obtained in this study were as follows : 1. The average temperature of the underwater surface was and the maximum was recorded at beginning of the August. 2. The evapotranspiration was gradually increased after transplanting and showed the peak from booting to heading stage of rice varieties. The average evapotranspiration through the whole growing period was 8. 43mm/day(Jinju) for tall statured Japonica variety, and 7.78mm/day(Taebaek), 7.71mm/day(Pungsan) for short statured Tongil varieties. 3. The ratio of evapotranspiration to pan-evaporation through the whole growing period was 1.71 for Japonica variety and 1.55 for Tongil varieties. 4. K-value in Blaney & Criddle formula was 1.41 for Japonica variety and 1.30 for Tongil varieties. Coefficient consumptive use of water (Kc-value) was 1.40 for Japonica variety and 1.27 for Tongil varieties. 5. It appeared that the water consumption in the 6, 8 cm pot is more than that of 2, 4 cm pot but the number of panicle of the 6, 8 cm pot is somewhat less than that of 2, 4 cm pot. The deeper water level is the less tiller became. It is consindered that 2 cm pot is more profitable than the others.