A theoretical model of irregular wave breaking and dissipation is developed. The setup of irregular waves is computed by means of radiation stress in association with the above wave breaking model. Amplitudes of surf beats are estimated with an empirical formula based on the wave observation near the shoreline. These three are combined to form a numerical model of wave deformation in the surf zone. The validity of the numerical model is confirmed by irregular wave experiments and field observation data. The results of the study are summarized with a method of wave height estimation in the surf zone.