To provide a door mounting structure capable of ensuring large door opening, and securely supporting the door to a vehicle body.

The door mounting structure 1 comprises an upper hinge 12 and a lower hinge 13 regulating a rotating shaft 5 of the door 4, and a vehicle body side supporting member disposed above a wheel arch 24 and supporting the upper hinge 12 and the lower hinge 13. A lower arm 16 connected to the door 4 side and belonged to the lower hinge 13 extends so as to separated downward from an upper arm 12 connected to the door 4 side and belonged to an upper hinge 12.