When a storage apparatus receives a write request for a storage area in LU0, an owner access processing unit judges whether write processing for the storage area is restricted with reference to a lock information table. When it is restricted, the owner access processing unit does not perform write processing for the storage area, and, if it is not restricted, the owner access processing unit sets a write processing restriction in a column of the storage area of the lock information table and performs write processing for the storage area. If other storage apparatuses receive the write request for the same area, the owner access processing unit transmits the lock reservation request to restrict write processing for the area of the LU, and if they receive acceptance of the lock reservation request from this storage apparatus, the owner access processing unit performs write processing for the storage area.