  N=2 supersymmetric U(N) Yang-Mills theory softly broken to N=1 by the
superpotential of the adjoint scalar fields is discussed from the viewpoint of
the Whitham deformation theory for prepotential. With proper identification of
the superpotential we derive the matrix model curve from the condition that the
mixed second derivatives of the Whitham prepotential have a nontrivial kernel.
