An apparatus, method and system for device management of a mobile communication terminal are provided. Various errors which may occur in the mobile communication terminal are monitored by the mobile communication terminal and are corrected remotely. In the method, the mobile communication terminal receives DiagMon policies from a DM server and stores the DiagMon policies in real-time in which the DiagMon policies are constructed in response to various errors. The mobile communication terminal monitors then the status of the mobile communication terminal according to periods set in the DiagMon policies. When a trouble is detected to occur, the mobile communication terminal collects detailed information related to the occurred trouble and transmits the detailed information to the DM server. The mobile communication terminal receives DiagMon correction information capable of correcting the occurred trouble from the DM server and corrects the trouble, and therefore normalizes the terminal.