Provided is a ferrule which includes a positioning mechanism configured to position an optical fiber having a predetermined outer diameter, and a recess configured for an adhesive to be disposed therein and having a first inner wall from which a front end of the optical fiber portion positioned by the positioning mechanism is protrudable, and a second inner wall opposite to the first inner wall. A distance between the first inner wall and the second inner wall is less than or equal to four times the outer diameter of the optical fiber.