1. A computer system comprising a management computer, among a plurality of computers, for dividing a job including data and a program for processing the data into a plurality of divided jobs and managing them, and a plurality of execution computers for executing divided jobs assigned by the management computer among the plurality of divided jobs, wherein each execution computer generates a job request including information about a number of the divided jobs based on a load on each execution computer and sends the generated jobs request to the management computer; and wherein when the management computer receives the ob request from each execution computer, it assigns a divided job to each execution computer according to the number of divided jobs included in the job request, wherein each execution computer measures a throughput value indicating the number of divided jobs, which can be processed per unit time, and a number of executed jobs indicating the number of divided jobs to be executed, respectively as the load for each load status observation time; decides multiplicity indicating the number of divided jobs, which can be executed simultaneously by each execution computer, based on the measured throughput value; calculates a difference between the decided multiplicity and a measured number of executed jobs; adds the calculated difference as a number of requested divided jobs to the job request; and sends the job request, to which the number of requested divided jobs is added, collectively to the management computer.