This paper describes a structural design process of arch-like truss based on the integrated design optimization (IDO) with force density method (FDM). The FDM has been considered as a very efficient traditional form-finding method and so it is consistently introduced as an individual technique in the present IDO process to decide a shape of the structure. The present IDO process includes several individual optimization techniques such as size optimization and topology optimization and additionally the intermediate processes connecting between two individual optimization techniques. Finally, numerical results of IDO for arch-like truss are described.