Lattice-shaped cement treatment by using the deep mixing method and others has been used as a liquefaction countermeasure, where the cement treatment normally reaches un-liquefiable stratum. In terms of the economic pursuit of ground improvement, the method to reduce the improvement depth was investigated by a series of model tests and numerical analyses in the present study. The studies described that a liquefaction countermeasure could be seen to synchronize the movements of un-liquefiable stratum and floating and cemented soil solid, which was formed by reducing the improvement depth.