A large number of methods have been developed to quantify the cell traction force and its distribution owing to its unique significance in the field of biocytology and tissue engineering. Silicon nanopillar arrays are excellent materials for measuring the force and preventing the problems of other methods because of their excellent mechanical strength and spatial resolution. In this study, silicon nanopillar arrays were prepared by laser interference lithography, and nanopillars were bent by cells after culture for a certain period of time because cells started to migrate along a certain direction. Finite element analysis was conducted to simulate the relationship between the cell traction force and the corresponding lateral displacement. We found that the displacement is positively associated with the transverse force, the average traction force of one single osteoblast measured by Si nanopillars was 8.5 μN and the maxima was 10.8 μN.