A lens barrel with a cam mechanism, manufactured by molding plastic, comprising a plurality of cams having a plurality of parting lines, for lens driving, and a plurality of cam followers that are engaged with the plurality of cam faces of the respective cams. The plurality of parting lines are arranged on the plurality of cam followers in a manner that the positions of the parting lines relative to the respective cam followers are set to be different from each other. In the driving of lenses, no two cam followers are simultaneously positioned at their respective parting lines so that the lenses may be free from the effect of a step at each parting line. Thus, the deviation of the position of each lens is minimized.