This report analyzed the theoretical transient vibration of chassis of the walking type rice transplanter which get over the obstacle by the wheels in the paddy field of hardpan. Since the seedlings that are putted on the seedling tray must be considered the mass and moment of inertia of seedling mats as function of time, the differential equation of motion of chassis are nonlinear differential equation and it is difficult to obtain the analytical solution. Because the transient response is the phenomenon of short period, if the decrease of mass of the seedling mats can be neglected, the differential equation of motion can be solved as the linear differential equation. Simulation of the optimum parameters of the elements of suspension will be also investigated by the method of experimental design.