The object of the present invention is to provide a camless valve driving device, without having a cam mechanism, which can reduce the valve driving energy and enhances fuel efficiency. According to the one preferred aspect of the present invention, the valve driving device of an internal combustion engine includes a pressure chamber, to which actuating fluid, to drive opening and closing of a main valve serving as an intake valve or as an exhaust valve of the internal combustion engine, is supplied; a first actuating valve for supplying high-pressure (Pc) actuating fluid to the pressure chamber during a prescribed period (tCP1) of the initial valve opening period of the main valve; a second actuating valve for introducing low-pressure (Pf) actuating fluid to the pressure chamber after the prescribed period (tCP1) has elapsed; a third actuating valve for discharging actuating fluid from the pressure chamber when the main valve is closed. According to the another preferred aspect, the valve driving device of an internal combustion engine further includes a valve spring and a magnet to impel the main valve toward the closed direction. Accordingly, the holding force of the main valve during the main valve opening period is restrained to the minimum, and the valve driving energy is decreased.