A lens actuating device includes a fixed member, an adjustable member, a driving unit and a movable support unit. The adjustable member is movably disposed in the fixed member along an optical axis, and has a lens module disposed therein. The driving unit is disposed between the fixed member and the adjustable member to provide a driving force for the adjustable member. The movable support unit is disposed at one side of the adjustable member opposite to the driving unit and has a first guiding structure formed on an inner side of the fixed member parallel to the optical axis, a second guiding structure, and a plurality of rolling members. The rolling members are configured into two rows and are disposed between the first and second guiding structures to fix the seconding guiding structure such that the displacement of the adjustable member is constrained along the optical axis.