A lens barrel includes a zoom optical system in which a focal distance is changeable; a first group frame moving together with the first lens group; and first and second cam mechanisms transmitting drive force to the first group frame. In a zoom region, each of a first group cam groove and a cam slot includes a first section, a second section which adjoins the first section and has an absolute value of a gradient smaller than that of the first section, and the third section which adjoins the second section and has the absolute value of the gradient larger than that of the second section, and in which a sign of the gradient is the same as that of the first section. A distance from an imaging surface to the first group frame in the optical axis direction has a local minimum in the second section.