In this study, the mediating effect of grit was examined in the effect of play teaching efficacy on play support competency by dividing the upper and lower groups according to the level of major satisfaction of pre-serviced early childhood teachers. To this end, 112 four-year early childhood education majors in D City were identified whether they took lectures on the 2019 revised Nuri curriculum, and the upper and lower groups were classified according to the level of major satisfaction, and each group's play teaching efficacy, grit, and play support competency were measured through questionnaires. The data of the study were analyzed through reliability verification, correlation analysis, t-test, multiple regression analysis, and Sobel test for mediating effect verification using the SPSS 20.0 program. As a result of this study, the play teaching efficacy, grit, and play support competency of preserviced early childhood teachers all showed the positive correlations, and there were significant differences depending on the major satisfaction of pre-serviced early childhood teachers. Next, in the upper group with the highest level of major satisfaction, the play teaching efficacy and grit of prospective early childhood teachers had a significant effect on the play support competency, but the mediating effect of grit was not significant. On the other hand, in the sub-group with low major satisfaction level, the play teaching efficacy and grit of pre-serviced early childhood teachers had a significant effect on the play support competency, and the mediating effect of grit was also found to be significant. The results of this study are expected to be meaningful in preparing measures to provide continuous experience and practice of teacher training institutions to enhance the play support competency of pre-serviced early childhood teachers to practice the play-oriented 2019 revised Nuri curriculum in the kindergarten.