A lens barrel (1, 2, 3) configured to be detachably attached to a camera body, comprising: a fixed tube section (10, 20, 30) that has a base end (10a, 20a, 30a) installable on the camera body, a top end (10b, 20b, 30b), and a first pitch screw section (10d, 20d, 30d) being formed on an inner peripheral surface (10c, 20c, 30c) of the fixed tube section (10, 20, 30); a movable tube section (11, 21, 31) that is a tube member configured to hold a plurality of lenses (A 1, A 2) and has a second pitch screw section (11b, 21b, 31b) formed on an outer peripheral surface (11a, 21a, 31a) of the movable tube section (11, 21, 31), and is located so as to be movable inside the fixed tube section (10, 20, 30) in such a state that the second pitch screw section (11b, 21b, 31b) is threadedly engaged with the first pitch screw section (10d, 20d, 30d), the plurality of lenses (A 1, A 2) including a first lens (A 1) and a second lens (A 2); and a nut member (12, 22, 32) that is configured to restrict a relative rotation between the fixed tube section (10, 20, 30) and the movable tube section (11, 21, 31) by abutting on the top end (10b, 20b, 30b) of the fixed tube section (10, 20, 30), being screwed to the second pitch screw section (11b, 21b, 31b), the movable tube section (11, 21, 31) comprising: a first side movable tube section (210, 310) that has a third pitch screw section formed on an outer or inner peripheral surface of the first side movable tube section (210, 310) and holds the first lens (A 1); a second side movable tube section (211, 311) that has a fourth pitch screw section formed on an inner or outer peripheral surface of the second side movable tube section (211, 311), and is attachable to the first side movable tube section (210, 310) in such a manner that the fourth pitch screw section is screwed to the third pitch screw section and holds the second lens (A 2); and a first fixed diaphragm plate (212, 314) that is located to between the first lens (A 1) and the second lens (A 2) and is detachable from the first side movable tube section (210, 310) in such a manner that the second side movable tube section (211, 311) is detached from the first side movable tube section (210, 310). a fixed tube section (10, 20, 30) that has a base end (10a, 20a, 30a) installable on the camera body, a top end (10b, 20b, 30b), and a first pitch screw section (10d, 20d, 30d) being formed on an inner peripheral surface (10c, 20c, 30c) of the fixed tube section (10, 20, 30); a movable tube section (11, 21, 31) that is a tube member configured to hold a plurality of lenses (A 1, A 2) and has a second pitch screw section (11b, 21b, 31b) formed on an outer peripheral surface (11a, 21a, 31a) of the movable tube section (11, 21, 31), and is located so as to be movable inside the fixed tube section (10, 20, 30) in such a state that the second pitch screw section (11b, 21b, 31b) is threadedly engaged with the first pitch screw section (10d, 20d, 30d), the plurality of lenses (A 1, A 2) including a first lens (A 1) and a second lens (A 2); and a nut member (12, 22, 32) that is configured to restrict a relative rotation between the fixed tube section (10, 20, 30) and the movable tube section (11, 21, 31) by abutting on the top end (10b, 20b, 30b) of the fixed tube section (10, 20, 30), being screwed to the second pitch screw section (11b, 21b, 31b), the movable tube section (11, 21, 31) comprising: a first side movable tube section (210, 310) that has a third pitch screw section formed on an outer or inner peripheral surface of the first side movable tube section (210, 310) and holds the first lens (A 1); a second side movable tube section (211, 311) that has a fourth pitch screw section formed on an inner or outer peripheral surface of the second side movable tube section (211, 311), and is attachable to the first side movable tube section (210, 310) in such a manner that the fourth pitch screw section is screwed to the third pitch screw section and holds the second lens (A 2); and a first fixed diaphragm plate (212, 314) that is located to between the first lens (A 1) and the second lens (A 2) and is detachable from the first side movable tube section (210, 310) in such a manner that the second side movable tube section (211, 311) is detached from the first side movable tube section (210, 310). a first side movable tube section (210, 310) that has a third pitch screw section formed on an outer or inner peripheral surface of the first side movable tube section (210, 310) and holds the first lens (A 1); a second side movable tube section (211, 311) that has a fourth pitch screw section formed on an inner or outer peripheral surface of the second side movable tube section (211, 311), and is attachable to the first side movable tube section (210, 310) in such a manner that the fourth pitch screw section is screwed to the third pitch screw section and holds the second lens (A 2); and a first fixed diaphragm plate (212, 314) that is located to between the first lens (A 1) and the second lens (A 2) and is detachable from the first side movable tube section (210, 310) in such a manner that the second side movable tube section (211, 311) is detached from the first side movable tube section (210, 310).