A user interface device (1) includes a display unit (2) which displays a first work space assigned to a user and a second work space different from the first workspace; a detection unit (3) which detects a position of the user; a calculation unit (4) which calculates an appropriate distance between the user and the second work space according to a type of an application program controlled by the user through the first work space; and a notification unit (5) which notifies the user that a distance between the position of the user detected by the detection unit (3) and the second work space is shorter than the appropriate distance calculated by the calculation unit (4).