In the thin plate bending problem, a formula is derived for the stress concentration at the end of a rounded notch in a clamped edge. Two different stress states in the vicinity of the notch are considered, i.e., the stress states symmetric and antisymmetric to the bisector of the notch angle. Three kinds of stress concentration at the end of the notch are investigated. It is shown that the stress concentration can be given by an infinite series expressed in terms of the radius of curvature and Williams order of stress singularity. A rational mapping function and complex stress functions are used for the analysis of the displacement boundary value problem. Examples of the stress distribution are also presented.