To heighten radiator element cooling effect to prevent braking oil from boiling by forming a cooling air duct extending between an inlet opening part and an outlet opening part facing at least one of radiator elements, inside a caliper body.

This disc brake 1 is provided with a caliper body 2 and a disc 3 and obtains braking force by pressing two pads 4, 5 mounted to the caliper body 2, to the disc 3 by pressure means 6, 7 supported to hub side and wheel side long-shaped elements. The respective pressure means 6, 7 are provided with hydraulic pistons 14, 17, but in this case, radiator elements are mounted to the pad side ends of the respective pistons 14, 17, and a duct 19 serving as a passage of cooling air fed through a feed pipe 24 to cool each radiator element is formed inside the caliper body 2. The respective pistons 14, 17 are cooled by the supply of the cooling air through the radiator elements.