Juglans mandshurica belongs to the family Juglandaceae is known to contain a wide range of pharmacological activities including anti-cancer, anti-inflammation, astringent, and anti-human immunodeficiency virus-type 1 (HIV-1). Melanogenesis refers to the biosynthesis of melanin pigment in melanocytes. In this study, to investigate the whitening activity of the extracts from Juglans mandshurica, we measured effects on a tyrosinase activity, a melanogenesis, and a tyrosinase synthesis in the B16/BL6 melanoma cells and an antioxidant activity. The extracts significantly scavenged a 1,1-diphenyl-2-picrylhydrazyl (DPPH) and a superoxide anion radicals in a dose-dependent manner with a $SC_{50}$ value of $20;{mu}g/mL$ and $25;{mu}g/mL$, respectively. Also, the tyrosinase activity and melanogenesis were significantly inhibited by the extracts. Furthermore, the synthesis of tyrosinase protein was significantly decreased by the extracts in enzyme-linked immunosorbent assay. Double blind study on the clinical efficacy of a cream containing 2% of the extracts showed that the extracts have a significant skin whitening effect. Therefore, this study demonstrates that the extracts from Juglans mandshurica may be useful as a potential agent for skin whitening.