In this paper, soft union ring (SU-ring) on a soft set is defined by using union operation of sets. This new concept shows how a soft set effects on a ring structure in the mean of union and inclusion of sets and from this overview, it functions as a bridge among soft set theory, set theory and ring theory. Then, its basic properties are derived and the relationship between soft intersection ring defined in [N. Cagman and F. Cıtak and H. Aktas, Soft intrings and its algebraic applications, Journal of Intelligent and Fuzzy Systems, 28 (3): 1225-1233 (2015)] and SU-ring are investigated. Furthermore, we give the applications of SU-ring to ring theory.