To provide a disk brake securing good operation efficiency.

The disk brake 1 includes a piston holding mechanism 34. In the piston holding mechanism 34, when rotational outputs are applied from deceleration mechanisms 36 and 37, a screw mechanism 52 linearly moves to cause a piston 12 to generate thrust in a disk direction, and the thrust in the disk direction is stored in the piston 12 by linear movement of a ball-and-ramp mechanism 28 and, when the rotational outputs from the deceleration mechanisms 36 and 37 are stopped, the thrust stored in the ball-and-ramp mechanism 28 is applied to the piston 12. Thus, high operation efficiency is secured.