In this paper non-L.P. optimizing technique was applied to the most economic design of composite breakwater and the computer program was developed. We have ever decided the economic sectional form from experiences or trials at preliminary design but using this program we can obtain the most economic mound hight and caisson width in about 10 seconds and so.
　This program contains several assumptions in equations and numerical calculation but we think this program become useful for investigation of the cost if those assumptions are improved for the future.