Human cognitive functions are associated with health conditions and lifestyles in daily living. However, little is known about how cognitive functions in healthy elderly people are correlated with their health conditions and daily lifestyles. This study investigated this issue. The study involved 85 healthy older adults, who were examined for memory and frontal-lobe functions. Additionally, their subjective health-related QOL (HQOL) and lifestyles were assessed, including the physical, intellectual, and social activities in daily lives. This study yielded three main findings. First, HQOL scores were positively correlated with scores for memory and frontal-lobe tasks. Second, older adults whose daily lives included moderate physical activity showed better memory functions than those with high and low levels of physical activity. Third, participants who engaged in a higher frequency of intellectual and social activities had better memory and frontal-lobe functions. Individual differences in subjective health condition and lifestyles could predict cognitive abilities in elderly.