An apparatus (1) for calibrating an ADAS sensor of an advanced driver assistance system of a vehicle (9), comprises: a base unit (2); a support structure (3) connected to the base unit (2); a vehicle calibration assistance structure (4), including a first surface which has a first combination of predetermined graphical features and which can be associated with the support structure so that the first surface, at an operating position, faces towards the service area (8); a flexible panel roller assembly connected to the support structure and including a roller and a flexible target panel (40).