The parallel computing system is provided with: plural computing nodes that perform a computation; a management node that is connected to the plural computing nodes, and that manages parallel computing by the plural computing nodes; and an external memory that is connected to the management node, that is accessible from the management node and the plural computing nodes, and that uses a semiconductor memory as a memory medium. The management node allocates data to be processed to each of the computing nodes, and creates an individual data file for each of the computing nodes in the external memory, and each of the computing nodes performs a computation by accessing the external memory and by reading the data file allocated to itself and a different data file to be referenced in a computation using the allocated data file, and outputs a computation result to the external memory.