Mirror sensor fixed on a windscreen

The unit includes an optical sensor (2) for activating windscreen wipers and an internal rear view mirror (3) fixed in a holder (11) between the sensor and vehicle roof. The mirror holder (11) has a first fixing part (12) interacting with a second fixing part (13). A socket (16) fixed on the windscreen is dimensioned so that the mirror foot (10) fixed on the mirror holder has a predetermined distance from the windscreen which is greater than the minimum spacing required for fitting the mirror foot so that required angular adjustment of mirror is possible. A cover fixed on the windscreen in the region of the sensor and mirror holders forms a sight screen for the sensor and fixing parts of the mirror.