To obtain a desired retract function on a slide hole side annular seal part of a pin boot.

There is provided a disc brake in which annular outer peripheral seal surfaces 23b1a, 23b1b being in pressure contact with a bottom wall surface 41b1 of an annular storage groove 41b, and elastic regulation parts (23b1c, 23b1d) are formed on an outer circumferential part 23b1 in a slide hole side annular seal part 23b of a pin boot 23. The elastic regulation parts (23b1c, 23b1d) are elastically engaged with both side wall surfaces 41b2, 41b3 of the annular storage groove 41b respectively to elastically regulate the rotor-axial-direction movement of the slide hole side annular seal part 23b within the annular storage groove 41b. On the inner circumferential part 23b2 of the slide hole side annular seal part 23b, an inner circumferential annular groove 23b2a which is opened toward an outer circumferential surface 21a of a support pin 21 is formed on a rotor-axial-direction middle part, an annular first lip part 23b2b which is in slide contact with the outer circumferential surface 21a of the support pin is formed on the bellow part side of the inner circumferential annular groove 23b2a and an annular second lip part 23b2c which is engaged with the outer circumferential surface 21a of the support pin in an elastically deformable fashion and has the retract function is formed on the anti-bellow part side of the inner circumferential annular groove 23b2a.