A resource allocation system calculates a performance ratio and a cost for each of a plurality of service tiers. For each of the service tiers, the performance ratio is a ratio of the intended performance to an agreement performance, the agreement performance is a performance that serves as a reference performance of the service tier, the intended performance is a performance calculated for the service tier, and the cost is based on a used capacity of an allocated storage resource among the storage resources belonging to the service tier. The system displays a service tier map that has an axis corresponding to the performance ratio and a second axis orthogonal to the axis and corresponding to the cost. A display object is placed, for each service tier, at a position according to the calculated performance ratio and the calculated cost of the service tier on the service tier map.