While lower serum albumin concentration is often found in the elderly, a relation between serum albumin and age has not been fully elucidated. We conducted population-based cross-sectional and 5-y longitudinal study to examine the relation. A total of 22,705 male and 40,149 female, aged 65 y and older, living in Gifu, participated in the health check service conducted by Gifu City Medical Association. They were self-supported in the activity of daily living and 3,438 of them were followed up every year from 1999 to 2003. Serum albumin levels decreased with age in both men and women. In the cross-sectional study, median value declined from 4.3 g/dL in males aged 65-69 y to 3.9 g/dL in 90≤ y, and 4.3 g/dL to 4.0 g/dL in females. Incidence of hypoalbuminemia (serum albumin≤3.5 g/dL) increased in parallel with age from 1.2% (65-69 y) to 6.6% (85-89) in males, and 0.6% to 4.1% in females. In the longitudinal study, regression analysis showed a significant decline in serum albumin of 0.015 g/dL per year (r=−0.716) in males, and 0.012 g/dL per year (r=−0.794) in females. Relative reduction of serum albumin in 5 y was larger in advanced age; 1.2% in females aged 65-69 y and 3.1% in 85-89 y (p<0.05), but not in males. In conclusion, a fall in serum albumin concentration in community-dwelling, self-supported elderly persons was associated significantly with aging.