To provide a horizontal one point disconnector capable of reliably extinguishing an arc generated between contactors in a shorter time than that of a conventional horizontal one point disconnector especially in action disconnecting an electric circuit.

A horizontal one point disconnector comprises: two rotary insulators which are separated by a prescribed distance, vertically-erected individually, and rotatable in the mutually same direction around the shaft center in the vertical direction; two rod-like blades whose mutual directions are made to be 180 degrees by fixing one end of each blade to each upper end of the rotary insulators, while contactors capable of attaching to and detaching from each other are provided at other ends of the blades; and a drive system for driving each of the rotary insulators. The horizontal one point disconnector makes an electric circuit open/close by rotating each of the rotary insulators to make each of the blades rotate in the same rotary direction normally or reversely and causing the respective contactors at the other ends to attach to or detach from each other. Preferably, one of the contactors has a salient in plan view, and the other of the contactors has a recess engaging with the salient, where a cross-sectional shape in the horizontal direction of the salient is formed to be an involute shape in plan view.