In the disk brake, mounting portions of the caliper of a disk brake extending toward the entrance side and the exit side with respect to the rotation direction of the disk. Relative to the rotation direction, the length of the mounting portion on the entrance side is greater than that of the mounting portion on the exit side so that the cylinder portion is offset toward the exit side. Further, the mounting portion on the entrance side has thickenings formed to extend in a longitudinal direction thereof, so that with respect to the direction of the axis of the disk, the thickness of the mounting portion on the entrance side is greater than that of the mounting portion on the exit side. During braking, when a bending moment acts on the caliper, which can cause inclination of the caliper relative to the disk, flexural rigidity of the mounting portion on the entrance side is higher than that of the mounting portion on the exit side.