Abstract: A door wheel includes a casing approximately having a form of "", a climbing frame approximately having a form of isosceles triangle and a portion of which is rotatably fixed on the casing, a roller rotatably installed on the climbing frame, a wedge approximately having a form of right-angled triangle and the inclined surface of which is adjacent to the surface corresponding to the fixed end of the climbing frame and which can be rectilinearly moved in the casing, and a control screw which is rotatably installed in the casing to rectilinearly move the wedge and one end of which is coupled with the wedge. The free end of the climbing frame can be climbed together with the roller by moving the wedge through rotating the control screw.