Lens barrel and image pickup apparatus that realize increased shooting magnification and slimming down

A lens barrel including a zoom mechanism that moves along an optical axis between a shooting state and a retracted state to change shooting magnifications, comprising:

• a first lens holding unit configured to hold a first lens and be movable along the optical axis;
• a cam follower disposed on an outer peripheral side of said first lens holding unit, and configured to follow cam grooves formed in a cam cylinder to move along the optical axis, and when moving from the retracted state to the shooting state, engage with said first lens holding unit to move said first lens holding unit from the retracted state to the shooting state;
• an urging unit interposed between said cam follower and said first lens holding unit, and configured to urge said cam follower and said first lens holding unit in such a direction as to draw said cam follower and first lens holding unit away from each other, and when said cam follower moves from the shooting state to the retracted state, engage with said first lens holding unit to move said first lens holding unit toward an image plane;
• and
• a restriction unit configured to, when said first lens holding unit moves toward the image plane, come into abutment with said first lens holding unit in the retracted state of said first lens holding unit, and restrict movement of said first lens holding unit toward the image plane,
• wherein when said first lens holding unit comes into abutment with said restriction unit with the movement of said first lens holding unit toward the image plane, and said first lens holding unit does not move toward the image plane, said urging unit is compressed to cause said cam follower to be moved toward the image plane.