a keyboard support bracket structure fastened to a underside of a desktop and movable horizontally and vertically relative to the desktop to a desired position for keyboard operation consists of a mounting bracket fastening to the desktop , an upper arm pivotally engaged with the mounting bracket through a first axle , a side arm pivotally coupled on two sides of the mounting bracket through a second axle , and a holding bracket pivotally engaged with the upper arm through a third axle . by releasing the constrained position of the holding bracket and the brake element of the side arm , the first , second , and third axles may be moved to perform vertical adjustment endlessly . the keyboard support structure thus made uses a fewer number of elements and may be moved with less effort to facilitate keyboard operation and conform to ergonomics .