An apparatus for generating a task-based User Interface (UI) includes a task ontology unit for maintaining task information with respect to the task, a device ontology unit for maintaining device information with respect to a device, a UI description generation unit for reading the task information and/or the device information using the task ontology unit and/or the device ontology unit, respectively, and generating UI description information from the read task information and/or the read device information, the UI description information being made by a task-based language, and a UI description parsing unit for parsing the UI description information to output the task-based UI.