A device management apparatus is adapted to be connected to devices which constitute at least one device group. An application is running in the device management apparatus. Each of the device managers is associated with one of the devices and is operable to create usage information of the associated one of the devices. A device group manager is associated with the at least one device group and coupled to the device managers to receive the usage information from each of the device managers. The device group manager is operable to notify the usage information in response to an inquiry from the application.