The invention concerns a pressure sensor including means of sensing pressure and converting pressure into an electrical signal able to be transmitted by an electrical circuit to an control interface circuit of an indicator device, wherein said sensing and conversion means include: a closed volume and a liquid contained in the closed volume, said liquid being electrically conductive and capable of moving inside said closed volume, at least one sensing member arranged inside the closed volume in a given position in said volume, said sensing member including at least one pair of electrodes and cooperating with the liquid when said liquid moves in the closed volume, so that said electrical circuit is closed when the liquid passes said sensing member. The pressure sensor is intended to be integrated in a pressure measuring device, particularly a timepiece.