  In this paper, we construct a supersymmetric composite axion (c-axion) model
based on the gauge group $SU(N)\times SU(M)$, which is one possible physical
application of the N=1 duality. The dual of SU(M) is interpreted as the color
gauge group. We illustrate the existence of c-axion for the case of one dual
quark in the dual gauge group $SU(\tilde M)$.
