To provide a disc brake device which prevents earth and sand from invading into a disc rotor and easily discharge invading earth and sand without damaging a heat radiation of the disc rotor.

A disc brake device 22 is equipped with: a disc rotor 19 fixed in a hub 13 of wheel 2; and caliper and dust cover 25 attached to a knuckle 3 rotatably supporting the wheel 2, and covers the disc rotor 19 from vehicle width direction inner side by the dust cover 25. The dust cover 25 is arranged in the inner space S of the disc rotor 19. An invasion preventing wall, which extends from an attaching section of the knuckle 3 to radially outer side and is adjacently arranged in the inner circumferential surface of the disc of the disc rotor 19, is formed in the dust cover 25, and a plurality of ellipse-like openings are formed in the invasion preventing wall.