The present study examined the effects of enzymatically hydrolyzed collagen peptides on the level of hippocampal neurogenesis and emotional behavior in adult mice. For this purpose, two kinds of enzymatically hydrolyzed collagen peptides, the lower or higher molecular weight peptides (LP: below 2,000, HP: about 30,000) were administered orally to C57BL/6 mice for 4 weeks. As a result, the density of proliferating cells in subgranular zone of hippocampus showed a 1.2-fold increase in LP mice as compared with HP mice. Additionally, LP mice spent less time in closed arms than HP mice in elevated plus maze test to examine anxiety-related behavior. These results suggest that oral administration of the lower molecular weight peptides derived from collagen enhanced the hippocampal neurogenesis and exerted emotional behavior in adult mice.