The nonlinear lateral characteristics of a lifting-body type reentry vehicle were improved. First, the reasons for the nonlinear lateral characteristics were investigated by CFD analysis. The results indicated that fins mounted on the Japan Aerospace Exploration Agency's (JAXA) baseline lifting-body configuration cause unsymmetrical development of vortices and result in nonlinear lateral characteristics. An efficient optimization algorithm, called EGOMOP (Efficient Global Optimization for Multi-Objective Problems), was adopted to improve these nonlinear lateral characteristics. EGOMOP predicts potential optimum solutions based on the probability estimated by the Kriging model. The computational time for optimization was markedly reduced due to use of the Kriging model. Further investigations were also performed to determine the effects of the upswept upper-aft and swept-back fin angles. The results indicated that the swept-back fin angle is an important factor controlling the lateral characteristics of the lifting-body type reentry vehicle.