Abstract: A protection device (10) having a set (11) of protection inflatable members (15, 20, 25) including left and right inflatable lateral means (20, 25) that are suitable for co-operating respectively with the left and right shoulder straps (6, 7), said device (10) possessing an inflator (30) for inflating said protection inflatable members (15, 20, 25). The device includes a headrest (35) carrying a nape airbag (15) of said set of inflatable members (15, 20, 25), the nape airbag (15) including one passage (16, 17) per inflatable lateral means (20, 25) in order to convey fluid to each inflatable lateral means (20, 25), said headrest (35) being provided with a hollow support (40) carrying said inflator (30) and with a fluid diffusion box (50) arranged in the nape airbag (15) so as to convey a fluid from the inflator (30) to the nape airbag (15) and to the inflatable lateral means (20, 25).