Objective: This study aims to investigate the effects of science activities related to seasonal customs on young children’s scientific inquiry abilities and communicative competences. Methods: Participants consisted of twenty-six 5-year-old children who were going to day care center in Gwangju metropolitan city. Half of them belonged to the experimental group and the other half to the comparative group. The experimental group participated in science activities related to seasonal customs, and the comparative group participated in science activities according to the Nuri curriculum. Results: The results of this study showed that scientific inquiry abilities and communicative competences of the young children in the experimental group were meaningfully improved. That is to say, the scores of the five sub factors of scientific inquiry abilities and the two sub factors of communicative competences of the experimental group were meaningfully higher than those of the comparative group. Conclusion/Implications: It is significant that this study provides basic information for future science activities related to seasonal customs that will be conducted in the early childhood field.