To reduce cost by facilitating processing by forming a female screw hole in a roller side arm.

An arm 15 is protruded on the lower end inner side of a door, a roller is supported by a tip of this arm 15, this roller is engaged with a rail provided on a car body, and a door is slided to be opened and closed in this slide door roller support structure, where the arm 15 is separated to be composed of a door side arm 15a and a roller side arm 15b, with the roller side arm 15b positioned under the door side arm 15a, thereby both arms 15a, 15b are tightened to each other.