To provide a lower runner structure of a suspending door capable of being applied also to those suspending doors other than folding doors, facilitating a setting operation of a lower runner to a lower rail, and reducing a damage to the lower rail and the lower runner.

A lower runner structure of a suspending door comprises a lower rail 1 which is set on a floor surface F and has an upper opening 11 and an inner space 12 communicating with the upper opening 11 and a lower runner 2 which is installed on the lower side of a suspending door D having a top part which supports a load and has a block member 21 which runs through the upper opening 11 on the lower rail 1 and the inner space 12. The block member 21 of the lower runner 2 has a horizontal cross-section formed in a circular shape and a large diameter part 213 on the lower end part of it. In the lower rail 1, a width (c) of the upper opening 11 is formed smaller than the large diameter part 213 of the block member 21 of the lower runner 2, and a width (d) of an inner space 12 is formed larger than a width (e) of the large diameter part 213. The large diameter part 213 of the block member 21 of the lower runner 2 is inclined to move the one side lower end to the inner space 12 of the lower rail 1 so as to set the dimensions so that the other side upper end of the large diameter part 213 can be passed through the upper opening 11 of the lower rail.