To facilitate inventory management and to reduce assembly man-hours by reducing the number of components by half in an adapter for an optical connector.

A housing of the adapter comprises: division bodies divided into two in an insertion direction; sleeve holders provided back to back in the insertion direction respectively integrally with the division bodies, and provided with an engaging piece for connection; a split sleeve mounted on both the sleeve holders; and a shutter mounted on one opening of the division body and integrally formed with a metallic spring thin plate which demonstrates dustproof and light-shielding functions. The shutter is formed roughly in a chevron shape as a whole, reinforced by a reinforcement part bent to an inner side at a part of a side face of a light shielding part, provided with a bent part formed roughly in a chevron shape, and formed such that the light shielding part is energized with respect to a base part in a lid closing direction of the opening by energizing force of the bent part and a distal end of the light shielding part is abutted to an inner wall of one opening to shield light, and the distal end of the light shielding part is bent to the inner side.