The purpose of this study was to examine the effects of eco-education by hands-on natural activities on the prosocial behavior of toddlers. The subjects in this study were 14 toddlers at a daycare center in the city of Y, South Jeolla Province. An experiment was implemented in 20 sessions, and the findings of the study were as follows: First, the eco-education by hands-on natural activities served to boost the prosocial behavior of the toddlers. Second, the eco- education by hands-on natural activities served to improve the subfactors of their prosocial behavior, involving helping, sharing, tolerating, conceding and friendship