The invention is directed to a load sharing method in a computer system including a first storage subsystem, a host computer, and a management computer. In the computer system, the first storage subsystem creates a plurality of first logical units from a storage area of a disk drive group, and the host computer creates a logical storage area configured by a plurality of virtual logical units respectively corresponding to the first logical units. A communications path is set between the host computer and each of the first logical units configuring the logical storage area. The load sharing method includes the steps of: monitoring, by the first storage subsystem, a load of its own; and changing, by the first storage subsystem, the communications paths between the host computer and the first logical units based on the monitoring result of the load. With such a configuration, provided is a computer system high in extensibility not deteriorating the performance at the limit of the system after load sharing among the storage subsystems.