An information processing system comprises a memory module having a plurality of unit memory regions, a memory controller, connected to the memory module via memory interface, configured to control access to the memory module, an error detector, which is in the memory controller, configured to perform an error detection on data read from the memory module, a failure inspection controller configured to switch a mode of the memory controller from a normal mode to a failure inspection mode, read data from an address, where data was written, to be inspected for each of the plurality of unit memory regions, cause the error detector to detect an error in the read data and perform a failure inspection and a determining unit configured to determine a memory failure or a transmission path failure on the basis of the state of the error detected from the unit memory regions.