To provide a lens driver with which prescribed zoom values and arbitrary aperture values are combined and set, using a simple constitution.

A lens barrel 1, into which this lens driver is built, has a cam ring 3 which is fitted turnably to a stationary frame 2, first and second group lens frames 4 and 5 which are fitted advanceably and retreatably into the cam ring 3 and an aperture ring 6 which is turnably supported at the first group lens frame 4. The cam ring 3 is provided with diagonal cam grooves, which drive the lens frames 4 and 5 to stepwise zooming positions, circumferential cam grooves which are held in the respective zoom positions and the aperture cam grooves which drive the aperture ring 6. The lens frames 4 and 5 turn the cam ring 3 in a state of being fixed and positioned to the respective zoom positions and turn the aperture rings 6, thereby enabling setting the aperture value of a photographic lens.