The object of the present invention is to provide a technique in which, in a storage apparatus using a PCI Express switch in an internal network, an EP can be shared among processors even if the EP is incompatible with the MR-IOV. A storage apparatus according to the present invention is provided with a first interface device which controls data input/output to and from a higher-level apparatus, and the first interface device is further provided with multiple virtual function units which provide virtual ports. The first interface device enables any of the virtual function units and does not enable any of the other virtual function units (see FIG. 14).