Brake device

A brake device comprising:

• a brake pad;
• a pad propulsion part connected to the brake pad and configured to move the brake pad linearly;
• and
• a caliper body including a cylinder part on which the pad propulsion part is accommodated,
• wherein the pad propulsion part includes:
• a conversion assembly converting rotation motion into linear motion;
• and
• a piston connected to one end of the conversion assembly,
• the conversion assembly is accommodated inside the cylinder part, the piston is entirely located outside the cylinder part,
• one end of a moving nut is inserted into an inside of the piston and includes a first groove disposed along a circumference of the moving nut,
• the piston includes a second groove at a position corresponding to the first groove on an inner surface of the piston, and
• the brake device further includes a seal part having a ring shape located in a space provided by the first groove and the second groove.