Provided is a ferrule holding member with a transparent body attached to an inner hole of a sleeve. The transparent body has a primary end face for bringing into contact with an end face of a plug ferrule at a halfway position in an axial direction of the sleeve. The primary end face of the transparent body has a convex curved surface obtained through heat treatment. The convex curved surface is preferably an unpolished surface, and a region with a radius of 75 μm or more, centered around a shaft axis of the sleeve at the convex curved surface, has a convex spherical surface. Alternatively, the transparent body is directly fixed to an inner surface of the sleeve through heat treatment.