The purpose of this study was to develop and apply the dietary education program for prescehoolers to improve their vegetable intakes. In this study, 134 mothers of preschoolers were surveyed about the problem of unbalanced food habits in children. A nutrition education program was developed based on the survey results, and then applied in the field to evaluate the effects of nutrition education. Most preschoolers (79.9%) had a relatively low intake of vegetables. The main reason for their unbalanced eating of vegetables was due to texture (34.6%) and taste (30.8%). The activity-based nutrition education program to increase vegetable intake consisted of four lessons. After the nutrition education program was administered for 43 preschoolers, their nutrition knowledge score significantly increased (P<0.001). Preschoolers found the lessons fun (90.9%) and interesting (81.4%), and said they would eat more vegetables in the future (88.4%). This study demonstrates that the unbalanced diet of preschoolers could be modified through the proper introduction of an education program.