the main sash the auxiliary sash is provided with a second vehicle interior wall abutting a first vehicle interior wall of the main sash a second vehicle exterior wall abutting a first vehicle exterior wall and a second bottom wall coupling the second vehicle interior wall and the second vehicle exterior wall a notch that is notched alongside the first vehicle exterior wall is formed solely at the second vehicle exterior wall the bottom end of the notch is disposed below the tip side of the second bottom wall and the top side of the second vehicle interior wall formed contiguously application_number US 201414916453 A description embodiments of the present invention are described below with reference to the accompanying drawings in the description left and right indicate left and right with reference to an occupant of a vehicle in which the vehicle door is mounted and front and rear indicate front and rear with reference to the travel direction of the vehicle in the drawings fr indicates front rr indicates rear ce indicates lateral center up indicates up and dw indicates down reference will be made to fig1 and 2 a door mounted on the rear right side of a vehicle body is shown as an example of a vehicle door 10.