Fatty acid activation gene (FAA1) in sake yeast Kyokai no. 701 (K701) was disrupted to investigate the accumulation of ethyl caproate in sake mash. Ethyl caproate, recognized as an important apple-like flavor in sake, is generated by fatty acid synthesis in yeast cells. The disruptant for the FAA1 gene (K701 Delta faa1) exhibited a reduced growth rate in a medium containing cerulenin and myristic acid or oleic acid compared with that of the parental strain (K701). In a sake brewing test in which the rice used was polished to 60% of its original size, the fermentation ability of K701 Delta faa1 was inferior to that of K701 but the production of ethyl caproate by K701 Delta faa1 was 1.6-fold higher than that by K701. These results suggest that the FAA1 gene in sake yeast plays an important role in sake brewing and the accumulation of ethyl caproate.