PURPOSE: To insert a modular plug from two reverse directions.

CONSTITUTION: An adaptor housing 14 is made of a synthetic resin, having a T-shape as the whole, and formed of a square pillar-like upper, cylindrical part 15, and a square pillar-like vertical cylindrical part 16 continued downward from the central lower surface of the upper cylindrical part 15. A modular plug 17 to be inserted and connected to a modular connector provided on a network equipment H is provided on the lower end part of the vertical cylindrical part 16, and modular plug sockets 24 capable of inserting the modular plug 11 are formed on both lateral end parts of the upper side cylindrical part 15, and connected in parallel to each other by an internal circuit. A double-insert is movably provided in the upper cylindrical that, when the modular plug 11 is inserted to one socket 24, the insertion of the plug 11 to the other socket 24 is arrested.