In this study, it focused on the thin mortar layer applied to adjust the height of precast PC slab and steel girder. The effect of the thickness of thin mortar layer and the arrangement of headed stud on the shearing force of studs was examined by the push-out test. As the result, the stud shearing force lowered as the thickness of the thin mortar layer was thicker. In addition, the stud shearing force of the test specimen in which the headed studs were grouped arrangement was lower than the test specimen in which the headed studs were single arranged row. In addition, the examination was carried out for the proposal of the new design formula of the headed stud shearing force considering the thin mortar layer.
