A disc brake including: a piston; a cylinder including a bore portion, which movably accommodates the piston, and a step portion formed on an opening end side of the bore portion; and a piston boot arranged between a tip side of the piston and a small diameter step portion of the cylinder. The piston boot includes: a large diameter annular fitting portion containing an annular metal member so as to be fitted to the small diameter step portion; a bellows portion, which extends from the large diameter fitting portion, is increased in its diameter from the large diameter fitting portion to an outer peripheral side, and is also deformed and extended from the large diameter fitting portion toward an inner peripheral side; and a small diameter fitting portion formed at an end portion of the bellows portion so as to fit to an outer periphery of the piston.