Patent ID: 8459421

Claim:
A disk brake comprising: a piston that presses a brake pad to a disk rotor; and a caliper at which the piston is slidably provided through a piston seal, the caliper making the piston moved forward by hydraulic pressure, wherein the piston has a piston base body made of aluminum alloy, an anodized film layer formed by an anodized treatment on a surface of the piston base body, and a chromium plating layer directly laminated on a surface of the anodized film layer, and wherein the anodized film layer has a thickness in a range of 1.0 and 10.0 μm, pores with a diameter of 40 nm or more which are formed by the anodized treatment are distributed on the surface of the anodized film layer with a density of 30 to 100 pores/μm 2 , and the chromium plating layer has a film thickness of 15 μm or more.