The potential of bioethanol production from rice is estimated in Thailand. The population decrease as well as rice consumption decrease per capita has been seen in Thailand like in Japan. If this trend continues, surplus arable land will come out. If irrigation, fertilizer input, and high yield rice are adopted on this surplus land, the increase of rice production will be expected. On the basis of this idea, three cases are assumed. Case (1) is ethanol production priority case, (2) self sufficiency of feed case, and (3) food priority case. According to the estimation, 1.1 million kL for E10, which is the national target of Thai Government, can be possible in any case. In cases (3), E10 can be possible by irrigation and fertilizer input. Except case (3), 20 million KL of bioethanol production can be possible by irrigation, fertilizer input, and high yield rice adoption. For comparison, the estimation is made for 2050.