This paper is concerned with a Discrete Ray Tracing Method (DRTM) for
the electromagnetic wave propagation along ground plane with arbitrary shape. The DRTM carries out two types of discretizations. One is discretization of rough surface, and the othre is discretization of serching ray. Much computation time can be saved by this operations. In the numerical result, we first make arbitrary shapes of ground plane by using a map data and calculate electromagnetic field distribution along it. Ray distributions are shown and the effect of diffraction in the shadowing region is discussed.