Proposed is a storage controller and its control method for speeding up the processing time in response to a command in a simple manner while reducing the load of a controller that received a command targeting a non-associated logical volume. This storage controller includes a plurality of controllers for controlling the input and output of data to and from a corresponding logical unit based on a command retained in a local memory, and the local memory stores association information representing the correspondence of the logical units and the controllers and address information of the local memory in each of the controllers of a self-system and another-system. Upon receiving a command sent from a host computer, the controller determines whether the target logical unit is associated with the controller of a self-system or another-system based on the association information, and, when the logical unit is associated with the other-system controller, the controller transfers and stores the command to and in the corresponding other-system controller based on the address information.