An elevation device comprises: a carrier, including an upper vertical frame having the left side and the right side oppositely disposed with a pair of rail slots, wherein one inner wall in each of the rail slots is longitudinally formed with a positioning slot allowing a guide rail to be disposed and positioned; a support seat, including a seat plate having the rear end thereof vertically extended with a pair of wing pieces, wherein backsides of the pair of wing pieces are respectively and longitudinally pivoted with at least one roller, the circumference of each of the at least one roller is formed with a guide slot confining the guide rail, thereby enabling each of the at least one roller to be longitudinally slid along the guide rail; and a constant force spring, formed in a coiled status and connected between the upper vertical frame and the support seat.