To provide a horizontal one point disconnector that can unfailingly bring blade tips into contact even when blades are stopped just before the blades are connected or just after the blades are opened or when a relative angle between the blades is comparatively large.

A horizontal one point disconnector 1 has conductive blades 5 and 6. The conductive blades 5 and 6 can rotate in a horizontal direction about insulators 3 and 4, respectively. The insulators 3 and 4 are provided so as to be opposed to each other. The tips of the conductive blades 5 and 6 are configured so as to be able to contact with each other. A first contact part 51 having an involute curve and positioned on a first reference circle c1 centered on a column 3 is formed at the tip of the blade 5. A second contact part 61 having an involute curve and positioned on a second reference circle c2 centered on a column 4 is formed at the tip of the blade 6. The first contact part 51 and the second contact part 61 are made contactable by rotations of both blades 5 and 6.