Cracks are caused by drying shrinkage between the upper part of the underground parking lot and the apartment wall. As a result of the investigation, the distance between the apartment and the apartment is more than 45m, and the top slab of the underground parking lot is usually flat when there is not with steps. Therefore, the crack occurs more when the underground parking lot is a PC slab than a RC slab. In this study, the reduction of cracks was conducted by extending the slab, expanding the beam size, increasing the wall thickness, and installing a delay joint on slab. In each case, a finite element analysis was performed to examine the crack reduction method.