Alzheimer's disease (AD) is a progressive neurodegenerative disease, resulting in the loss of cognitive function. Mitochondrial aldehyde dehydrogenase (ALDH2) has been proposed to be a risk factor for the development of AD, but there is still controversy about that. In this study, we demonstrated the role of ALDH2 enzyme activity on amyloid-beta (Aβ) and nuclear factor kappa B (NF-κB) expression in mice brain following ethanol exposure for 8 weeks. Five male Aldh2 (+/+) and Aldh2 (-/-) mice, 8 weeks-old of age (C57BL/6J strain), in each group were exposed to ethanol for 8 weeks (2 g/kg wt./day) using gavage. Those in the control groups received 0.9% saline alone. Results showed a difference in expression level of Aβ in the hippocampus after ethanol exposure according to the ALDH2 enzyme activity (p<0.05), but not in the level of NF-κB. Our results suggest a possibility that ALDH2 enzyme activity may be an important role in the development of AD.