The present invention relates to a hair straightening device to be placed on an air blower, comprising a first straightening element and a second straightening element positioned on either side of an air diffuser (9), each of the two elements comprising an outer comb (1) and an inner comb (2), removably attached so as to allow a sliding movement of one relative to the other, said sliding movement of the two outer (1) or inner (2) combs allowing to grip the hair and to stretch it above the air diffuser (9), the teeth of the outer combs (1) being formed by a succession of arches (3) whose holes define two tunnels (4) that make space for the inner combs (2) in such a way as to allow an arrangement of said inner combs (2) beneath said outer combs (1) within said tunnels (4) and to allow said sliding movement of the inner combs (2) relative to the outer combs (1) in order to displace the teeth (5) of said inner combs (2) relative to the planes formed by the arches (3) of the outer combs (1).