Abstract: The present invention relates to a user input processing device using a limited number of magnetic field sensors, which senses a magnetic field from a magnetic field generator installed in a writing tool, such as a pen, using the limited number of magnetic field sensors, acquires information on a position and direction of a pen based on information on the sensed magnetic field and information on an input on a touch screen and a position of a hand of a user, and processes the acquired information as a user input. The present invention includes at least one magnetic field sensor for sensing a magnetic field, which are independent of each other, a touch inputter for sensing a touch of a writing tool or a hand, and a controller for calculating a position and direction of the writing tool or the magnetic field generator mounted in the writing tool based on a current touch position value of the touch inputter and a current magnetic field value from the magnetic field sensor.