Motor race is a key field, which helps to introduce new trends and technologies to a serial commercial production of cars. The presented research is focused on design optimization of a race car frame. The designed frame has a spatial structure. It is designed to ensure a proper interconnection of other structural units of a car, such as axles, elements of a powertrain and others. There are presented the results of optimization of the frame design. The optimized design comes from its initial design. The objective function of the design optimization was a minimization of displacement of the frame under the loads as well as a minimization of the bending displacement. Simulation software implementing the finite element method was used for research. Optimization process of the frame structure led to the reduction of torsional displacement of the front part frame by 45.58%, the rear part by 52.56% and the bending displacement by 14.36%.