1. A multiprocessor system comprising a plurality of processor nodes each including a memory having an independent memory space, wherein the processor nodes are connected via a plurality of communication lines, each of the processor nodes includes a memory mapping unit that performs a memory mapping for mapping a part or whole of memories of other processor nodes to the memory space in the memory of the processor node as remote memories according to a request from a process operated by an execution of a program, a first communication unit that performs a communication via a first communication line, a second communication unit that performs a communication via a second communication line, a first processor node, which is one of the processor nodes, further includes a memory-mapping managing unit that creates a mapping connection between a processor node and other processor nodes upon the memory mapping unit performing the memory mapping, the memory mapping unit transmits a memory allocation request for requesting allocation of the remote memories to the memory mapping units of the other processor nodes via the second communication unit, and transmits a connection creation request for requesting creation of the mapping connection to the memory-mapping managing unit of the first processor node via the second communication unit, and the memory-mapping managing unit creates the mapping connection between the processor node and the other processor nodes according to the connection creation request transmitted from the memory mapping unit, and then transmits a memory mapping instruction for instructing execution of the memory mapping to the memory mapping unit via the first communication unit of the first processor node.