a disk brake having members for keeping the friction pads in contact with the disk rotor in such a way that the wear of the friction members and the energy loss are kept to a minimum . the disk brake has a disk rotor , friction pads provided opposed to each other on both sides of the disk rotor , a caliper formed with a fluid pressure cylinder at least on one side of the disk rotor , and a piston slidably received in the cylinder for selectively applying braking force to the disk rotor by pushing the friction pads into sliding contact with the disk rotor . a resilient member is disposed between the piston and one of the friction pads provided opposite the piston for biasing the friction pads toward the disk rotor by a predetermined stroke , thereby keeping the friction pads in contact with the disk rotor at a predetermined surface pressure even while the brake is not applied .