Electric booster

An electric booster comprising:

• a motor part configured to be driven by power applied thereto;
• a body part mounted and fixed onto the motor part;
• a cylinder part coupled to the body part;
• a screw part connected to the motor part and rotated;
• a nut part embedded in the body part, and screwed to the screw part so as to linearly move;
• a first piston part constraining an end of the screw part, and moved to the cylinder part while being pressed by the nut part;
• a first elastic part supporting the first piston part;
• a second piston part supported by the first elastic part;
• and
• a second elastic part supporting the second piston part,
• wherein the first piston part comprises:
• a first piston tube part embedded in the body part and the cylinder part;
• a first piston inner wall part formed in the first piston tube part, and supported by the first elastic part;
• and
• a first piston protrusion part protruding from the first piston inner wall part toward the screw part, and limiting movement of the screw part.