The present study is to predict the multidiretional random wave height at the front face and concave corner of a refracted breakwater which is not straight. The numerical simulation on wave height at the front face of an insular breakwater is performed by using the boundary element method, and obtained results have been compared with those of exact- and analytical solutions of the eigenfunction presented by Goda et al. (1971) and the other existing numerical solution. Also, the results of wave-height distribution due to the refracted breakwater have been validated through comparisons with previous results of analytical solution. Based on the validation through these comparisons, several wave-height distributions at the interested region have been illustrated for various conditions related with concave corner angles and the wave incidence, and then the prediction of wave height are simulated at the front face and concave corner of a refracted breakwater under construction currently. Excellent agreements have been obtained in all cases, and this study can effectively be utilized for predicting random waves for various breakwater system.