A zoom lens barrel includes a base member 1001, a linear cylinder 700 fixed on the base member 1001, a cam cylinder 800 configured to be rotatable with respect to the linear cylinder 700, a ball member 701 and a pin member 702 provided on the linear cylinder 700, and a plurality of optical component units. The cam cylinder 800 includes a cam groove 800d that the ball member 701 contacts and that determines a position in an optical axis direction of the cam cylinder 800 with respect to the linear cylinder 700, and a cam groove 800i that the pin member 702 engages with in a radial direction of the cam cylinder 800 and that the pin member 702 contacts in two directions different from each other that are the optical axis direction.