PURPOSE: To provide a disk brake capable of keeping the sure braking performance, constituting two different brake systems, and miniaturizing the device with a simple structure.

CONSTITUTION: A disk brake device 10 is provided with a torque converting mechanism 42 and an ultrasonic motor 70. A supporting shaft 54 of an operation lever 52 is inserted in a core part of a screw shaft 46 of the torque converting mechanism part 42 in a relatively movable manner only in the axial direction. During the normal braking, the screw shaft 46 is moved in the axial direction by the ultrasonic motor 70, and an inner pad 14 is pressed to generate the braking force. When the operation lever 52 (the supporting shaft 54) is turned, the screw shaft 46 is moved in the axial direction while being turned, and the inner pad 14 is pressed to be in the braking condition, and can be used as the parking brake.