[en] In this paper, we deal with a design method for nonlinear systems, focusing on flat outputs of the dynamical systems. One of the main reasons why flat outputs are focused on is as follows. Once flat outputs are found for nonlinear systems, all we have to do is to apply a linear design method to such nonlinear systems, because the nonlinear systems may be transformed identically into the associated linear systems by means of flat outputs. However, the existing computation methods are complicated and not suitable to a control design from a practical point of view. For example, we sometimes meet the integrability issue concerning the flat outputs. This paper proposes a new type of practical computation method about how to circumvent the integrability issue of the flat outputs. Simulation is given for illustrating the usefulness of the proposed design method. (paper)