A bare optical fiber manufacturing method includes applying an ultraviolet curable resin applied around an optical fiber; and irradiating the ultraviolet curable resin with ultraviolet light emitted from semiconductor ultraviolet light emitting elements, by use of an ultraviolet irradiation device having plural ultraviolet irradiation units each having plural positions where the ultraviolet light is emitted toward the ultraviolet curable resin, the plural positions being arranged on the same circle, the plural ultraviolet irradiation units being arranged in a traveling direction of the optical fiber such that the optical fiber passes centers of the circles, at least two of the plural ultraviolet irradiation units being differently arranged with respect to circumferential direction angles thereof around an axis that is the traveling direction of the optical fiber.