To surely prevent a runner from being pulled out and removed by insert-fixing a fixing part formed at a cap main body into a rail tip part, close- operating a cap part connected or fitted to the cap main body in the state of being openable/closably and clogging the tip part of a rail.

As for this rail cap 1, the cap main body 2 is formed of synthetic resin such as poly vinyl chloride, a fixing part 3 for insert-fixing to between the edge parts 7b of the rail 7 is formed on the front tip side of the main body 2 and the cap part 4 formed to make a size/shape for clogging the tip part of the rail 7 is connected or fitted openably/closably to its rear tip side. In addition an abutting part 2a abutting on the tip part 7b of the rail 7 is formed on both side surfaces of the center part of the main body 2 and an insertion hole 2b for inserting a fixing member 6 such as a screw is formed on the center surface on its rear tip side. Thereby the runner is surely prevented from being pulled out and removed.