1. A method for generating a task-based user interface (UI) performed at a processor, the method comprising: receiving task selection input information from a user; reading task information corresponding to the task selection input information from a task ontology unit and device information from a device ontology unit, respectively; generating UI description information from the task information and the device information through a UI description generator, the UI description information being made by a task-based language; and parsing the UI description information through a UI description analysis unit to output the task-based UI; and analyzing a similarity between the devices based on at least one of task semantic information and device semantic information to automatically map the at least one of the task semantic information and the device semantic information, wherein the task-based language includes a device description section configured to describe a relationship with the device, an internal state of the device, and a variable for controlling a function of the device, a task description section configured to describe the task information being the processor configured to provide services to a user, and an interface description section configured to describe the task-based UI corresponding to the device information and the task information.