A collapsible lens barrel having a low-profile size and a camera applied with the collapsible lens barrel. The lens barrel includes a first retractable lens-retaining frame and a second retractable lens-retaining frame for retaining at least one of a plurality of lens groups and being retracted to a position outer than an inner radius of a movable lens cone in the collapsed state, respectively; and a first retractable lens-moving member and a second retractable lens-moving member. At least one of the first and second retractable lens-retaining frames is retained movable relative to the respective retractable lens-moving member along an optical axis direction in the collapsed state.