The invention concerns a device for marking a commercial article, comprising two separable parts:a first part (12) including an axial spike (14),a second part comprising an orifice for axial insertion of the spike and means for locking the spike inserted in said orifice.One of the parts, referred to as the attachment part, comprises an attachment: member (32) that is able to pivot between a first position in which a free end of the member is far away from the attachment part and a second position in which the free end is disposed in a housing (50) of the attachment part. The attachment part is configured so that the free end (32a) of the attachment member is blocked in the housing (50; 108) by the presence of the other part of the device that is locked to the attachment part by way of the spike (14) and its locking means.