Purpose: This study investigated the practices of preventing infectious diseases by daycare center teachers. The focus was on the mediating effects of self-efficacy in the relationship between communication skills and practices of preventing infectious diseases.Methods: This study used a descriptive correlational design. The participants were 164 daycare center teachers. Hierarchical regression was used to test the mediating effect of self-efficacy in the relationship between communication skills and practices of preventing infectious diseases. Data were analyzed using the independent t-test, one-way analysis of variance, Pearson correlation coefficients, and hierarchical regression. The mediation effect was analyzed using an SPSS Macro program, PROCESS.Results: Significant relationships were found between communication skills and practices of preventing infectious diseases (β=.19, <i>p</i><.001), self-efficacy and practices of preventing infectious diseases (β=.59, <i>p</i><.001), and communication skills and self-efficacy (β=.27, <i>p</i><.001). Self-efficacy had a significant mediating effect (β=.17, 95% confidence interval=0.07~0.29) on practices of preventing infectious diseases.Conclusion: In order to improve practices of preventing infectious diseases among daycare teachers, it is necessary to develop and apply interventions and methods that can increase effective communication skills and self-efficacy.