There are many literatures available on the numerical analysis of the deformation and the stress distribution of the reinforced rectangular plate under the lateral load. Those are, however, so unsatisfied in case of the actual numerical computation as follows ; (1) Many literatures are due to the theory of orthotropic plate. The theory can be available only under the condition that the rectangular plate has so many reinforcements which are distributed uniformly over the plate, and not available in case of a few reinforcements, or not-uniformly distribution. (2) In case of using the theory of orthotropic plate, we can analyze the whole plate macroscopically, but not microscopically. (3) In case of using the theory of orthotropic plate torsional rigidity of each stiffener can not be input to numerical analysis. (4) In case of using the finite element method, it takes much more computing time to get more accuracy in stress analysis. (5) Also in case of using the finite element method, in the analysis on the point just near the reinforcement, we have less accuracy. In this paper, numerical analysis is done more accurately for less time even in case of much more reinforcements by means of computing program due to the author's theory published formerly.