The present Structuralists have usually calculated the end Moment of Rigid-frame members by using the Moment Distribution Method, presented by Hardy Cross in 1930, on the Basis of Elastic Law. But this method is considered to be an unfinished solution in case of the moment condition, which the Non-Equilibrium distributed loads or the Horizontal Force acted upon it result in deflection. Hence, after finishing the calculation of stress by means of the Moment Distribution Method, the stress condition due to Horizontal Forces had to be corrected approximatly. However we can directly get the solution of Rigid-frame having sidesway not by above method but by the Moment Distribution computation. Consequently this method is regarded as a Perfect Moment Distribution Method. Here 1 present.