Nicotinamide adenine dinucleotide (NAD⁺) is an essential co-factor mediating numerous redox reactions. NAD⁺ is consumed as a substrate for poly(ADP-ribose) polymerase (PARP) and sirtuins and regulates various biological processes, such as metabolism, DNA repair, gene expression, and stress responses. In living organisms, the NAD⁺ levels are determined by a balance between NAD⁺ production and degradation. Recently, numbers of studies have demonstrated that NAD⁺ levels decline with age, and the deterioration of NAD⁺ metabolism promotes aging and aging-associated diseases, including metabolic diseases, neurodegenerative disease, and musculoskeletal diseases. Contrariwise, elevated NAD⁺ levels in tissue exhibit beneficial effects in both physiological and pathological aging. Various approaches, such as supplementation with NAD⁺ precursors, activation of NAD⁺ biosynthetic pathways, and inhibition of NAD⁺ degradation, have been used to increase NAD⁺ levels. In this presentation, I will show the recent progress regarding the role of NAD⁺ metabolism in aging and discuss the possibilities of NAD⁺ metabolism as a therapeutic target against aging