Door of a motor vehicle.

Door of a motor vehicle with an outer plate (10) of the door and an inner plate (11) of the door, provided with a cutaway portion (101), wherein the cutout portion (101) cover total or partially by a support plate (2) carrying mechanical components and / or electrical (27, 30, 32, 37, 38a, 38aa, 38b, 38bb, 38c), such as a window of window, a lock, an air cushion side impact protection (side airbag), an electronic equipment and electric cables, and with an inner lining (5) of the door, which is positioned in the vehicle door into the vehicle interior, being joined together in the form foldable against each other by a junction zone (6a, 6b, 6c, 6d, 6e) supporting plate (2) and at least a portion (5a) of the inner lining (5) of the door, characterized in that the support plate (2) and the part (5a) of the inner lining (5) of the door are configured as a constructional unit made together in a single tool, being linked together foldably against each other the support plate (2) and the part (5a) of the inner lining (5) of the door through a connecting region (6a, 6b, 6c, 6d) made in said tool simultaneously.