A fluid dispenser device including: a reservoir (10); a dispenser head (20) incorporating a dispenser orifice (21); a metering chamber (30); and a piston (40) that is slidable in the metering chamber (30) between a rest position and a dispensing position. The piston (40) is mounted in stationary manner on the reservoir (10) and made integrally with the reservoir (10) and/or with a fastener mechanism (100) adapted to be fastened on the reservoir (10).