Roman domination on a graph G is that we assign values 0, 1, or 2 to each vertex, subject to the condition that vertices whose assigned values are 0 need at least one vertex whose assigned value is 2 to be its neighbor. The weight of a Roman domination is the sum of all assigned values of the vertices. A graph G is a circular-arc graph if there exists a set F of arcs on a circle in which every arc corresponds to a vertex of G and if vertex v and vertex u have an edge if and only if their corresponding arcs are intersected. The Roman domination problem is finding a Roman domination whose weight is minimum among all possible Roman dominations. In this thesis, we want to find an algo-rithm to solve Roman domination problem on circular-arc graphs.