Abstract: In an outside mirror assembly for motor vehicles, having a mirror installed pivotably inside an enclosure fixed to a stay, the retaining force of a structure pivotably holding the mirror can be adjusted and the mirror can be detached and reinstalled. The holding structure can be removably installed by means of a fixture inside the enclosure fixed to the stay. A back plate holding the mirror is pivotably supported to the holding structure, and the force of the holding structure for retaining the back plate can be adjusted. The enclosure has formed therein an opening through which a tool for adjusting the retaining force of the holding structure and for removing or reinstalling the fixture can be introduced, and a cover is removably attached to the enclosure to close said opening.