Field measurements of wave height and the fraction of breaking waves on longshore bars and troughs are conducted at Hazaki Oceanographical Research Station(HORS) facing the Pacific Ocean. The fraction of breaking waves decreases toward the shore on a trough, and the decrease rate depends on topographic properties of the bar;the decrease rate increases as the water depth at the bar crest decreases or as the bar height, the difference between the water depth at the trough and that at the bar crest, increases. Field data obtained on the troughs show that the wave height-water depth ratio at wave reforming decreases as the wave period decreases. Compared with the wave height-water depth ratios in a small-scale experiment, most ratios in the field are small.
　Models for wave height and the fraction of breaking waves are developed; the models employ a wave-by-wave approach, where the shoaling, breaking and reforming of an individual wave are calculated. The performances of the models calibrated with experimental data are not satisfied;the fractions of breaking waves estimated by the models are smaller than the values measured on troughts. The models therefore are calibrated and verified with the field data. Furthermore, the validity of the models calibrated with the field data is confirmed with large-scale experiment data.