The present invention relates to a side airbag module intended for holding back, in the event of an impact, the occupant (13) of the seat (15) of an automotive vehicle with a reclining backrest (19) by means of suitable means including an adjustment knob (31), comprising a cushion (11) configured for being vertically deployed between the protection area required for the occupant (13) and the body of the vehicle when inflated with the gas provided by a gas generator and a distance piece (21) joined at one of its ends (23) to the cushion (11) and at the other end (25) to the reclining means of the backrest (19) such that its length is reduced when the inclination of the backrest (19) is increased so that the deployed cushion (11) can be properly positioned no matter what the required inclination of the backrest (19) of the seat (15) may be.