The invention relates to a lifejacket used in the field of safety equipment aboard a boat. The jacket comprises an inflatable vest having two faces opposite one another, which can be housed, folded, in a protective envelope, which comprises an external peripheral opening fitted with temporary closing means by which the vest can expand when inflated. The jacket also comprises a carrying harness to which the envelope can be fixed. The vest comprises inside at least one non-inflatable zone in which its two faces opposite one another are assembled, especially by thermowelding. Thus, this non-inflatable zone, inside the vest and not on its periphery, allows it to have a hooking zone for correct attaching of the vest, the protective envelope and the harness.