A ferrule for retaining a plurality of optical fibers includes a front end surface; a rear end surface; a plurality of fiber retaining holes; an accommodation hole; and a void portion. The fiber retaining holes each extend from the front end surface toward the rear end surface along a first direction. The accommodation hole is connected to the plurality of fiber retaining holes. The void portion is provided in a region around the plurality of fiber retaining holes. The fiber retaining holes include constant diameter portions extending from the front end surface along the first direction. The void portion is provided along the constant diameter portions, and is aligned with the constant diameter portions in a plane perpendicular to the first direction. A minimum value of a width in the plane of the void portion differs from an inner diameter of the constant diameter portion.