A fuel injector comprising: an injection nozzle; an injection valve, which is provided with a mobile plunger to adjust the flow of fuel through the injection nozzle; an electromagnetic actuator to move the plunger between a closing position and an opening position of the injection valve and provided with at least one electromagnet comprising a coil, a fixed magnetic armature, and a mobile armature, which is mechanically connected to the plunger and has at least one supply through hole for the passage of fuel towards the injection nozzle; a hydraulic braking device, which is coupled to the supply hole and has the function of hydraulically generating a braking force to decelerate the travel of plunger both when the plunger moves towards the opening position of the injection valve and when the plunger moves towards a closing position of the injection valve; a closing spring, which tends to hold the plunger in the closing position; and a supporting body with a tubular shape and provided with a central channel, which houses the fixed magnetic armature and the mobile armature; wherein the hydraulic braking device comprises: a valve element, which is coupled to the supply hole of the mobile armature and comprises an elastic blade, which is partially fixed to a surface of the mobile armature; and a stop element, which is coupled to the elastic blade and is arranged at a given distance from the elastic blade to stop an opening movement of the elastic blade itself in a fixed and predetermined position, the injector is characterized in that the hydraulic braking device comprises a spacer, which is interposed between the elastic blade and the stop element and establishes the axial distance existing between the elastic blade and the stop element. an injection nozzle; an injection valve, which is provided with a mobile plunger to adjust the flow of fuel through the injection nozzle; an electromagnetic actuator to move the plunger between a closing position and an opening position of the injection valve and provided with at least one electromagnet comprising a coil, a fixed magnetic armature, and a mobile armature, which is mechanically connected to the plunger and has at least one supply through hole for the passage of fuel towards the injection nozzle; a hydraulic braking device, which is coupled to the supply hole and has the function of hydraulically generating a braking force to decelerate the travel of plunger both when the plunger moves towards the opening position of the injection valve and when the plunger moves towards a closing position of the injection valve; a closing spring, which tends to hold the plunger in the closing position; and a supporting body with a tubular shape and provided with a central channel, which houses the fixed magnetic armature and the mobile armature; wherein the hydraulic braking device comprises: a valve element, which is coupled to the supply hole of the mobile armature and comprises an elastic blade, which is partially fixed to a surface of the mobile armature; and a stop element, which is coupled to the elastic blade and is arranged at a given distance from the elastic blade to stop an opening movement of the elastic blade itself in a fixed and predetermined position, the injector is characterized in that the hydraulic braking device comprises a spacer, which is interposed between the elastic blade and the stop element and establishes the axial distance existing between the elastic blade and the stop element.