To provide a method and the like for testing a main memory in a multi processor system, which is capable of reducing a test execution time and accordingly a start-up time as compared with the case where a single processor is used for the test. The present invention provides a method for testing a main memory (MM) in a multi processor system (MPS) including a main processor (MP) and multiple sub processors (SP) each having a DMA transfer mechanism and a local store (LS). The method and the like including: MP allocating a partial memory region (PMA) in MM to each SP; MP requesting each SP to test the allocated PMA; each SP filling LS thereof with initial data in response to receiving the request; each SP transferring the data stored in LS thereof to PMA by using a DMA transfer; each SP transferring the data stored in PMA to LS thereof by a DMA transfer; and SP testing the data in LS; and MP judging a test result on MM by putting together the tests results in response to the completion of all the tests by respective SP.