A brake device comprising: a main braking brake comprising: a main braking caliper body; a brake pad part including a first brake pad and a second brake pad that are arranged at one side and another side of the main braking caliper body and have first surfaces as friction surfaces facing each other; and a main braking piston configured to pressurize second surfaces of the first brake pad and the second brake pad to shorten a distance between the first brake pad and the second brake pad; and a parking brake comprising: a parking caliper body coupled to the main braking caliper body and including a locking part caught by the second surface of the first brake pad; and a parking piston installed on the parking caliper body and configured to pressure the second surface of the second brake pad, wherein the parking brake is configured such that, when the parking piston moves and pressurizes the second brake pad, the locking part of the parking caliper body moves the first brake pad toward the second brake pad, characterized in that: the main braking caliper body includes a guide hole extending in a direction parallel to a direction in which the parking piston moves, wherein the parking caliper body includes a guide rod inserted into the guide hole, and wherein the guide rod is configured to slide within the guide hole when the parking piston is driven, wherein the brake device further includes an assembly bolt coupling the guide rod to the parking caliper body. a main braking brake comprising: a main braking caliper body; a brake pad part including a first brake pad and a second brake pad that are arranged at one side and another side of the main braking caliper body and have first surfaces as friction surfaces facing each other; and a main braking piston configured to pressurize second surfaces of the first brake pad and the second brake pad to shorten a distance between the first brake pad and the second brake pad; and a main braking caliper body; a brake pad part including a first brake pad and a second brake pad that are arranged at one side and another side of the main braking caliper body and have first surfaces as friction surfaces facing each other; and a main braking piston configured to pressurize second surfaces of the first brake pad and the second brake pad to shorten a distance between the first brake pad and the second brake pad; and a parking brake comprising: a parking caliper body coupled to the main braking caliper body and including a locking part caught by the second surface of the first brake pad; and a parking piston installed on the parking caliper body and configured to pressure the second surface of the second brake pad, a parking caliper body coupled to the main braking caliper body and including a locking part caught by the second surface of the first brake pad; and a parking piston installed on the parking caliper body and configured to pressure the second surface of the second brake pad, wherein the parking brake is configured such that, when the parking piston moves and pressurizes the second brake pad, the locking part of the parking caliper body moves the first brake pad toward the second brake pad, characterized in that: the main braking caliper body includes a guide hole extending in a direction parallel to a direction in which the parking piston moves, wherein the parking caliper body includes a guide rod inserted into the guide hole, and wherein the guide rod is configured to slide within the guide hole when the parking piston is driven, wherein the brake device further includes an assembly bolt coupling the guide rod to the parking caliper body. the main braking caliper body includes a guide hole extending in a direction parallel to a direction in which the parking piston moves, wherein the parking caliper body includes a guide rod inserted into the guide hole, and wherein the guide rod is configured to slide within the guide hole when the parking piston is driven, wherein the brake device further includes an assembly bolt coupling the guide rod to the parking caliper body.