For the equivariant bordism groups of C "-manifolds with diίferentiable actions of Sl =U(ί) and its subgroups Zn , the cases of free actions have been studied by Conner-Floyd [3], Conner [2], Su [11], Uchida [13], Kamata [5, 6] and others. The purpose of this note is to study the ring structure of bordism for the cases of semi-free actions (cf. Alexander [1], Miscenko [8]). The authors express their thanks to the referee for his advice and careful reading of the manuscript.
