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