Inflatable device for motor vehicle occupant's head protection

An inflatable head protection device for occupants (1) of a motor vehicle is described, having an air bag (3) which deploys laterally to the head in the event of a side impact and prevents displacement of the head. The head protection device has a belt guide channel (4) through which the belt webbing (2) of a safety belt runs. In order to follow belt webbing movements, the head protection device is pivotally attached via a ball joint (8) to the upper edge of a seat backrest (14).