An elevating device for the worktable of a manual planer includes at least one base, one movable worktable and one elevating device. The elevating device comprises of a driving shaft, a driven shaft, a rotary base, a connecting rod base, a combining shaft and a spindle. When an operating member of the driving shaft is rotated, a driving gear of the driving shaft drives a first driven gear of the driven shaft to rotate, and a second driven gear of the driven shaft drives a third driven gear of the rotary base to rotate at the same time. Simultaneously, the rotary base is rotated to actuate the connecting rod base to operate, and the movable worktable positioned on the connecting rod base is moved upward or downward and is adjusted in its position.