Actuation device for actuating a hydraulic actuator such as a brake and/or clutch, in particular for motorcycles, the device comprising: - a device body provided with a tank of liquid, the device body defining a housing seat for at least one piston to pressurise said liquid inside the associable hydraulic circuit of the actuator, the housing seat having a main extension which defines an actuation direction (X-X) of the piston, the housing seat being in fluidic connection with the tank of liquid, - the device body supporting at least one actuation lever, adapted to influence the piston in actuation in a working stroke parallel to the actuation direction (X-X), - the piston comprising a stem which extends between an actuation end, at which it interfaces with the actuation lever and a thrust head adapted to pressurise the liquid in the hydraulic circuit of the actuator, - wherein the piston is elastically pressed by elastic means in contrast with the action of the actuation lever, adapted to influence the piston in a relief stroke opposite the working stroke, wherein the device comprises at least one stop adapted to determine the position at rest of the piston, said stop forming an end stop or stop to the relief stroke of the piston under the thrust of the elastic means, wherein - the stop is at least partially inserted inside the tank of liquid, and comprises at least one branch which crosses at least partially the housing seat of the piston through at least one insertion hole, the branch comprising an abutment which intercepts a portion of the piston, forming the stop to the relief stroke, characterised in that the stop comprises at least one branch which intercepts the stem, the stem having at least one recess in relation to the thrust head, so as to form a support and an undercut for said branch, along the actuation direction (X-X), and a limit stop abutment for the relief stroke. - a device body provided with a tank of liquid, the device body defining a housing seat for at least one piston to pressurise said liquid inside the associable hydraulic circuit of the actuator, the housing seat having a main extension which defines an actuation direction (X-X) of the piston, the housing seat being in fluidic connection with the tank of liquid, - the device body supporting at least one actuation lever, adapted to influence the piston in actuation in a working stroke parallel to the actuation direction (X-X), - the piston comprising a stem which extends between an actuation end, at which it interfaces with the actuation lever and a thrust head adapted to pressurise the liquid in the hydraulic circuit of the actuator, - wherein the piston is elastically pressed by elastic means in contrast with the action of the actuation lever, adapted to influence the piston in a relief stroke opposite the working stroke, wherein the device comprises at least one stop adapted to determine the position at rest of the piston, said stop forming an end stop or stop to the relief stroke of the piston under the thrust of the elastic means, wherein - the stop is at least partially inserted inside the tank of liquid, and comprises at least one branch which crosses at least partially the housing seat of the piston through at least one insertion hole, the branch comprising an abutment which intercepts a portion of the piston, forming the stop to the relief stroke, characterised in that the stop comprises at least one branch which intercepts the stem, the stem having at least one recess in relation to the thrust head, so as to form a support and an undercut for said branch, along the actuation direction (X-X), and a limit stop abutment for the relief stroke.