This study was intended to research the changes of self-expression ability and artistic self-expression of children with development retardation along with the change of self-expression at preschool and self-expression reaction per each session. The subjects of this study was a 4 year old boy who goes to Y preschool located in D city, received pediatrician's opinion that he has a developmental problem. The research tools were self-expression ability test and self-expression improvement scale. For the self-expression ability test, self-expression rating scale, which was developed by Rakos & Schroeder(1980) and translated by Byeon Changjin and Kim Seonghee(1980), was used. For the self-expression improvement scale, the one that was by Ji Hannae(2011). Data process first, for the change of self-expression ability, pre, post and follow up self-expression ability tests were done, and the results were compared. For the change of artistic self-expression, pictures drawn at early, middle and late stages were evaluated with the use of the and the results were bar charts. Second, for the change of self-expression at the class, self-expression ability was divided into linguistic and non-linguistic elements based on pre, post and follow up reports, Third, for the change of self-expression per each session, the changes of linguistic and non-linguistic self-expression were compared based on CCTV recording. This study self-expression ability and artistic self-expression of children with development retardation along with the change of self-expression at preschool reaction per each session caused a positive change.