A support device includes a slide frame defining a receiving space that has an opening suitable for facing a wall surface, a sliding unit slidable on the slide frame and suitable for connection with at least one of a display screen and a work platform, and a load-adjusting unit disposed in the receiving space, connected to the slide frame and the sliding unit, and switchable between a movable state, in which it is movable and brings the sliding unit to move therealong, and a locked state, in which it generates a supporting force that supports the sliding unit to maintain at a desired fixed point. A control unit is disposed on the sliding unit and includes an operating member for controlling the movement of the load-adjusting unit.