Using the method proposed by Woinowsky-Krieger, the influence function for deflection of a wedge-shaped plate with clamped boundaries is presented in this paper. From this function, a new influence functions for “Moment nucleus” is derived and then it is converted into an influence function for a wedge-shaped two-dimensional stress field under the action of “Contraction nucleus”. Using the solution thus derived, distortion of an finite plate with a slit due to “Contract nucleus” is studied and the application to welding mechanics of a butt-welded plate is briefly indicated.