the present invention provides a lens barrel applicable to digital cameras , image pickup devices and cell phones . the lens barrel is small , low - cost and high - performance , and can suppress , by means of a simple mechanism provided in the lens barrel , a variation in the focal position of the lens barrel caused by the change in temperature . the lens barrel comprises a lens group consisting of a plurality of lenses and a lens chamber for holding the lens group . an elastic member is provided between a set of adjacent lenses of the lens group , for urging the set of adjacent lenses in an optical axis direction of the lenses . the space between the set of lenses is increased or decreased by the elastic member , which causes a back focus of the lens barrel to move in a direction opposite to the direction in which the focal position of the lens barrel varies due to thermal expansion or thermal contraction of the lens group and the lens chamber and the change of refractive index of the lens group resulting from a temperature change . hence , by increasing or decreasing the space in the optical axis direction between the lenses at both ends of the elastic member , the variation in the focal position of the lens barrel is suppressed .