In the automobile steering system, tie-rod acts as a sacrificial component to protect the inner steering gear such as rack and pinion. Therefore, the allowable maximum buckling load is the crucial design constraint as well as minimum buckling load. The conventional tie-rod model was recognized to have excessive bucking load, so that it should be redesigned to reduce critical buckling load. In this paper, we investigate the optimal design of bent outer tie-rod including initial imperfection of buckling mode shape. However, the bent design causes mass gain, although it makes substantial decrease of critical buckling load. Therefore we set the multi-objective optimizing problem to minimize the value of critical buckling load and mass gain with two kinds of structure design variables (scale factor & bent length). We finally obtained the optimum parameters to reduce critical buckling load by 64.96%, with mass gain of 9.05%.