1. A parallel computer system, including a plurality of computing nodes for running a calculation program and a master node connected to the computing nodes via networks, for performing a parallel computation which requires a long time for computation as in a design optimization using an evolutionary algorithm, the system comprising: abnormality handling unit for automatically performing a series of processes of monitoring, periodically or on the basis of process unit, crash or hang-up of the calculation program, said handling unit suspending execution of the calculation program in the computing node in which abnormality has been detected and making another computing node execute the relevant calculation program, wherein the abnormality handling unit automatically: detects abnormality of values or formats of input/output files required for the computation, detects abnormality of parallel computation software in the computing node before execution of the calculation program and detects abnormality of the values and the formats of the output files where computation results are recorded after execution of the calculation program, suspends execution of the calculation program in the computing node in which abnormality has been detected, and making another computing node execute the relevant calculation program.