A partition priority controlling apparatus includes a partition ID identifying unit, a partition ID match detecting unit for detecting whether or not a partition to which one of a plurality of system board modules belongs matches partitions to which the other system board modules respectively belong for at least one combination of the system board modules, and an inter-crossbar-unit conflict partition detecting unit for detecting a combination of partitions, which make a conflict between two of a plurality of crossbar units, for at least one combination of the two crossbar units on the basis of the determination result of the partition ID identifying unit, and the detection result of the partition ID match detecting unit.