A lens barrel to be attached to a camera body, the lens barrel comprising: a fixed cylinder that is formed in a cylindrical shape and fixed to the camera body; a first lens holding frame that holds a lens, is disposed on an inner circumferential side of the fixed cylinder, and capable of moving in an optical axis direction of the lens relative to the fixed cylinder; a guide cylinder that is formed in a cylindrical shape, disposed on an outer circumferential side of the fixed cylinder, and capable of moving, together with the first lens holding frame, in the optical axis direction relative to the fixed cylinder; and a rotary cylinder that is formed in a cylindrical shape, disposed on the outer circumferential side of the fixed cylinder, and capable of rotating about a rotation axis a direction of which is the optical axis direction relative to the fixed cylinder, wherein when a side to be attached to the camera body in the optical axis direction is defined as a back side, and the side opposite to the back side is defined as a front side, a front end section of the guide cylinder and the rotary cylinder are disposed further on the front side than a connection part that connects the first lens holding frame and the guide cylinder, and a first power transmission mechanism is provided between the front end section of the guide cylinder and the rotary cylinder, the first power transmission mechanism converting a rotary motion of the rotary cylinder into a linear motion of the guide cylinder in the optical axis direction to cause the guide cylinder and the first lens holding frame to move in the optical axis direction. a fixed cylinder that is formed in a cylindrical shape and fixed to the camera body; a first lens holding frame that holds a lens, is disposed on an inner circumferential side of the fixed cylinder, and capable of moving in an optical axis direction of the lens relative to the fixed cylinder; a guide cylinder that is formed in a cylindrical shape, disposed on an outer circumferential side of the fixed cylinder, and capable of moving, together with the first lens holding frame, in the optical axis direction relative to the fixed cylinder; and a rotary cylinder that is formed in a cylindrical shape, disposed on the outer circumferential side of the fixed cylinder, and capable of rotating about a rotation axis a direction of which is the optical axis direction relative to the fixed cylinder, wherein when a side to be attached to the camera body in the optical axis direction is defined as a back side, and the side opposite to the back side is defined as a front side, a front end section of the guide cylinder and the rotary cylinder are disposed further on the front side than a connection part that connects the first lens holding frame and the guide cylinder, and a first power transmission mechanism is provided between the front end section of the guide cylinder and the rotary cylinder, the first power transmission mechanism converting a rotary motion of the rotary cylinder into a linear motion of the guide cylinder in the optical axis direction to cause the guide cylinder and the first lens holding frame to move in the optical axis direction.