An optical-fiber-attached ferrule of the invention includes: an optical fiber; and a ferrule that holds an end portion of the optical fiber, where the ferrule includes a ferrule end surface, a fiber hole to insert the optical fiber, an adhesive-filling section that includes an opening surface of the optical fiber hole and an opposed surface opposed to the opening surface, and a light transmitting part that transmits an optical signal between the ferrule end surface and the opposed surface, and an end surface of the optical fiber is disposed close to the opposed surface in the adhesive-filling section The adhesive-filling section is filled with an optical adhesive with Shore hardness D of equal to or less than 50.