An object of the present invention is to provide a disk brake and a method of making the disk brake capable of improving the efficiency of manufacturing a caliper. A bottom portion 41 of a bore 40 is formed by integrally welding an opening surrounding portion at the bottom portion 41 side of a cylinder portion 35 and a bottom cover member 92 fitted to the opening surrounding portion by friction stir welding. The bottom cover member 92 is formed into a disk shape, and provided with a protrusion 68 at one surface side facing the interior of the bore 40, and an inflow hole 58 for a supply of a fluid pressure into the bore 40 formed within the range of the protrusion 68 to establish communication between one surface 71 and the other surface 63.