To obtain large capacity, high quality future mobile satellite communication systems, we must use a multi-beam that has extremely high levels of frequency reuse. This paper describes a novel resource allocation scheme for multi-beam satellite communication systems that can dynamically offer maximum communication capacity without compromising quality. The scheme optimizes the frequency bandwidth, satellite transmission power, modulation level, and coding rate to each beam to deal with the ever-changing user distribution and inter-beam interference conditions. First, to minimize interference, we clarified the optimal constraint conditions when all clusters share the same bandwidth, while consuming the system bandwidth. We then used them as constraints in the optimization algorithm that allocates resources to each beam. Second, to manage the various needed resources and adapt them to the beam gain and interference levels at user locations, we propose two schemes for allocating resources within a beam. As a result, although both schemes were able to accommodate the same number of users, the fixed power with adaptive modulation secured a more stable communication quality. This means that our scheme can satisfactorily allocate multi-beam satellite resources, while increasing communication capacity and improving quality.