Abstract: A method of obtaining whole-grain rice power with higher added value by using brown rice after GABA enriching treatment to unhulled rice, in which heated/humidified air is applied to the unhulled rice, treatment for enriching a GABA content contained in the unhulled rice is executed and then, the unhulled rice is dried to a predetermined moisture and subsequently, the unhulled rice is hulled to obtain brown rice, the brown rice is subjected to grain-sorting so as to extract immature rice, and the immature rice is milled to obtain the whole-grain rice powder, whereby a high added value can be given to immature rice which conventionally only had to be sold inexpensively.