A user interface device which allows a first user to operate one or more objects displayed in a first work space assigned to the first user and which allows a second user to operate one or more objects displayed in a second work space assigned to the second user, said user interface device comprising: a display unit configured to display the first work space assigned to the first user; a detection unit configured to detect a position of the first user in front of the display unit and to detect a gesture of the first user; and a control unit configured to control display of an independent object, wherein the independent object is an object that belongs to no user and is to be released by the second user when the detection unit detects a releasing gesture performed by the second user indicating that the object is to be released, wherein said control unit is configured to: determine whether the independent object is in a face-to-face space of said display unit, wherein the face-to-face space of said display unit is a space on the display unit and is in front of the detected position of the user; move the independent object in a mode which varies between when the independent object is in the face-to-face space and when the independent object is outside the face-to-face space; and stop the moving independent object in the first work space assigned to the first user when said detection unit detects an obtainment gesture performed by the first user indicating that the independent object is to be obtained, in, said control unit is configured to cause a moving speed of the independent object moving in the face-to-face space to be slower than a moving speed of the independent object moving outside the face-to-face space, and in, when the independent object moving at a slower moving speed is in the face-to-face space, said control unit is configured to (i) stop, in the first work space, the independent object moving at the slower moving speed, when said detection unit detects the obtainment gesture, and (ii) cause the moving speed of the independent object moving outside from the face-to-face space to be faster by terminating slowing down of the independent object, when said detection unit does not detect the obtainment gesture. a display unit configured to display the first work space assigned to the first user; a detection unit configured to detect a position of the first user in front of the display unit and to detect a gesture of the first user; and a control unit configured to control display of an independent object, wherein the independent object is an object that belongs to no user and is to be released by the second user when the detection unit detects a releasing gesture performed by the second user indicating that the object is to be released, determine whether the independent object is in a face-to-face space of said display unit, wherein the face-to-face space of said display unit is a space on the display unit and is in front of the detected position of the user; move the independent object in a mode which varies between when the independent object is in the face-to-face space and when the independent object is outside the face-to-face space; and stop the moving independent object in the first work space assigned to the first user when said detection unit detects an obtainment gesture performed by the first user indicating that the independent object is to be obtained,