Sarcopenia, an age-related decline in skeletal muscle mass and strength, causes the decline of the quality of life in the elderly. The age-related alteration in the differentiation potency of satellite cells, myogenic tissue specific stem cells in skeletal muscle, and preadipocytes in skeletal muscle is possibly involved in the disruption of homeostasis in skeletal muscle. The differentiation of the cells is affected by the microenvironment surrounding the cells, called niche. Here, we focused on SPARC (secreted protein acidic and rich in cysteine) as a secreted glycoprotein existing in the niche. We review the roles of SPARC on the differentiation of satellite cells and preadipocytes in the muscle and their alteration with age.