1. A load balancing method executed in a system having a storage and a plurality of information processing modules that can be shared among business services, comprising the steps of: registering a business configuration definition of each business service including a schedule of a corresponding business service in a business configuration management repository of said storage by a configuration unit of said system; storing a service level objective of each business service in a service-level-objective table of said storage by a service-level-objective unit of said system; storing information on performance of each of said plurality of information processing modules in a performance management table of said storage by said configuration unit; receiving a designation of a business service and reading the schedule of a designated business service from the business configuration definition registered with the business configuration management repository by a reservation unit of said system; acquiring from said service-level-objective unit the stored service level objective of the designated business service by said reservation unit; partitioning the schedule of the designated business service read from the business configuration definition into a plurality of partial schedules according to the acquired service level objective by said reservation unit; registering performance information for the plurality of information processing modules in a performance management table of said storage, respectively; registering in advance judgment information indicating contents of the start process and finish process of the plurality of partial schedules of each business service in the business configuration management repository; using a processor, comparing the judgment information of an already-reserved business service with the judgment information of the designated business service, and thereby selecting one or more information processing modules of said plurality of information processing modules whose performance information stored in the performance management table satisfies the service level objective in each partial schedule, reserving the information processing modules selected satisfying the service level objective in the partial schedules as information processing modules for executing the designated business service in the schedule in said storage, and omitting a step in a start process or finish process of the designated business service that coincides with a step of a business service that has already been reserved with the information processing module; and executing the designated business service with the plurality of information processing modules reserved in the receiving step.