A method for producing an optical fiber unit by winding at least two bundling members on an outer circumference of an optical fiber bundle formed by bundling a plurality of optical fibers, the method comprising: feeding the optical fiber bundle in a feeding direction from a fiber passage member; feeding the bundling members while forming intersection points between two of the bundling members on the outer circumference of the optical fiber bundle by feeding at least one of the bundling members from a bundling member passage part of a rotating member that surrounds the fiber passage member and is concentric therewith, while causing the rotating member to rotate around its longitudinal axis in both directions and thus undergo an oscillating rotation around the longitudinal axis; and fusion-bonding the bundling members at their intersection points by passing the optical fiber bundle and the bundling members through a heating unit that is arranged downstream from the fiber passage member and the rotating member in the feeding direction, and thus forming an optical fiber unit in which a winding direction, with respect to the optical fiber bundle, of said at least one of the bundling members is reversed at a fusion-bonded point between the bundling members, wherein: the rotating member includes a first rotating member that surrounds the fiber passage member and is concentric therewith, and a second rotating member that surrounds the first rotating member and is concentric therewith; and the first rotating member and the second rotating member undergo oscillating rotation around the longitudinal axis in opposite directions from one another. feeding the optical fiber bundle in a feeding direction from a fiber passage member; feeding the bundling members while forming intersection points between two of the bundling members on the outer circumference of the optical fiber bundle by feeding at least one of the bundling members from a bundling member passage part of a rotating member that surrounds the fiber passage member and is concentric therewith, while causing the rotating member to rotate around its longitudinal axis in both directions and thus undergo an oscillating rotation around the longitudinal axis; and feeding at least one of the bundling members from a bundling member passage part of a rotating member that surrounds the fiber passage member and is concentric therewith, while causing the rotating member to rotate around its longitudinal axis in both directions and thus undergo an oscillating rotation around the longitudinal axis; and fusion-bonding the bundling members at their intersection points by passing the optical fiber bundle and the bundling members through a heating unit that is arranged downstream from the fiber passage member and the rotating member in the feeding direction, and thus forming an optical fiber unit in which a winding direction, with respect to the optical fiber bundle, of said at least one of the bundling members is reversed at a fusion-bonded point between the bundling members, wherein: the rotating member includes a first rotating member that surrounds the fiber passage member and is concentric therewith, and a second rotating member that surrounds the first rotating member and is concentric therewith; and the first rotating member and the second rotating member undergo oscillating rotation around the longitudinal axis in opposite directions from one another. the rotating member includes a first rotating member that surrounds the fiber passage member and is concentric therewith, and a second rotating member that surrounds the first rotating member and is concentric therewith; and a first rotating member that surrounds the fiber passage member and is concentric therewith, and a second rotating member that surrounds the first rotating member and is concentric therewith; and the first rotating member and the second rotating member undergo oscillating rotation around the longitudinal axis in opposite directions from one another.