A protection device (10, 10′, 10″) for disc brakes of velocipedes of the racing bike, mountain bike, city bike, electric pedal assisted cycle, and/or small motorcycle type, which comprises an interchangeable brake guard (12, 16, 18), secured to a wheel (20) of the velocipede, arrange coaxially to a disc (14) and featuring a basically “C”-like cross-sectional profile which comprises a front side (12′, 16′, 17) intended for covering a front surface of the disc (14), a rear side (12″, 16″, 17′) intended for partially covering a rear surface of the disc in correspondence with a brake track which pads of a brake caliper (28) act on, and an intermediate side (12′″, 16′″, 17″) intended for connecting the front side (12′, 16′, 17) and rear side (12″, 16″, 17′) to each other and for covering a peripheral circumferential edge of the disc (14).