A parallel computer includes a plurality of calculation nodes and a management node. A calculation node includes a retention control unit that retains job information in a retention unit in association with an identification number, and the management node includes a retention control unit that retains the job information in a retention unit, retains, as a snapshot, job information of the same identification number in a case where the job information of the same identification number about a calculation node is detected in the retention unit. The retention unit of the calculation node includes a retention region enabling retention of job information corresponding to a plurality of periods, and the retention unit of the management node includes a retention region enabling retention of the job information corresponding to the plurality of periods with respect to each of the calculation nodes.