Abstract
　From the view point of the disaster prevention on a beach, it is very important to clarify the dynamics of wave deformations and successive wave breakings because this phenomena are closely related with the occurrence of longshore currents and the generation of breaking wave forces.
　This paper theoretically deals with the wave field on a slope including the breaker zone by means of the coordinate transformation from Cartesian coordinate to the elliptic. As the result, a tentative solution of the second order approximation about the wave steepness can be obtained as well as Stokes' wave theory.
　The validity of this solution can be ascertained in some extent by comparing with the experimental data obtained by Goda et al. and Iwagaki et al.

*金沢大学工学部
Faculty of Engineering, Kanazawa University