In front wheel drive cars (FWD) with transversely mounted engines, engine mounting is closely related to idle shake. For this reason, in the early design stage, consideration of the natural frequency of the engine mount system and idle shake simulation has been made primarily using the finite element model. However, these approaches do not have good accuracy. In the prototype stage, only mount rates can be controlled because modifications of mount locations are nearly impossible.This paper describes a method to find the optimum mount system. In this method, optimum locations and rates of mounts are automatically found through consideration of engine motion and body dynamic characteristics. Also, applying this to a four-cycle diesel engine with four mounts, the design method of mounts are discussed.