A slidable lens retracting device is provided for retracting a lens system that include lens group units all positioned on a common optical axis when the lens system is in an operational state. At least one lens group unit is retracted from the on-axis position on the optical axis to an off-axis space radially off the optical axis by the slidable lens retracting device when the lens system is moved to a retracted state. The slidable lens retracting device includes slides mounted to the lens group unit and fixed support members forming inclined surfaces with which the slides are engageable. The control tracks receive the slides therein and are movable along the optical axis to bring the lens system to the retracted position to cause the slides to engage and slide along the inclined surfaces and thus moving the lens group unit to the off-axis space.