Image processing apparatus comprises, a first USB interface which connects with an external processing apparatus, a second USB interface which connects with a data processing unit, and a control unit which controls data transfer between the first USB interface and second USB interface. The control unit notifies the data processing unit of management data, which is managed by the control unit, via the second USB interface. The data processing unit generates status data of the data processing unit, including the notified management data. In response to a request from the external processing apparatus, the generated status data is transmitted to the external processing apparatus via the first USB interface and second USB interface.