[en] A mass spectrum of composite particles is studied in a supersymmetric (SUSY) composite model with nonlinear interactions of F-type, which are taken to be invariant under SO(2, C). Composite particles are contained in a massive superfield and a massless Nambu-Goldstone superfield associated with spontaneous breakdown of SO(2, C). Through explicit SUSY- and SO(2)-breaking, a massless Nambu-Goldstone boson (NGB) and quasi Nambu-Goldstone fermion (QNGF) acquire masses, which are estimated to be: M sub(NGB)² asymptotically equals M sub(SS) M sub(CS) and M sub(QNGF) asymptotically equals M sub(SS) M sub(CS)/M (M sub(SS) << M sub(CS) << M) by use of Dashen's formula, where M sub(SS) is an SO(2)-singlet SUSY-breaking scale; M sub(CS) is a supersymmetric SO(2)-breaking scale; M is a mass of the massive superfield. (author)