Lens barrel and method for optical axis adjustment

Lens barrel includes first group lens frame unit, second group lens frame unit, lens frame, insertion hole, and depressions. First group lens frame unit holds lenses. Second group lens frame unit holds lens. Lens frame is disposed between first group lens frame unit and second group lens frame unit on an inner circumference side of first group lens frame unit through radial clearance. Insertion hole is provided on an outer peripheral surface of first group lens frame unit, and a jig of lens frame is inserted into insertion hole. Depressions are provided at a position accessible from an outside in a state where first group, second group lens frame units and lens frame are assembled, and fix lens frame to first group lens frame unit.