Objective: The purpose of this study is to investigate the effects of parental humor style on their children s emotional expressiveness. Methods: Parental humor styles and their children s emotional expressiveness were measured in 306 parents and their 153 young children enrolled in a infant educational institution located in Seoul and Gyeong-gi Province. A total of 459 subjects participated in this study. The data were used in producing basic statistics and a t-test and regression analysis with SPSS 21.0 program were performed. Results: First, parents with young children were found to use humor above the medium level in interaction with their children, especially societal humor. Second, societal, self-expansive, and self-defeating humors used by mother were found to predict children s emotional expressiveness, while the humor used by fathers was found to have no effect on children s emotional expressiveness. Conclusion/Implications: The parental use of humor is a common phenomenon these days and is aimed at creating more intimate parent-child interaction. In addition, it was found that mother s humorous interaction can bring about positive emotional expressiveness in her child.