To prevent lowering and unstableness of magnetic force and trouble caused by influence of muddy water or the like entered between the magnetic encoder (21) and a magnetic sensor (6), a sealing apparatus (4) comprises an approximately C-shaped protecting annular member (11) fitted to one of an inner member (1) and an outer member (2), a first encoder member (12) having a cylinder portion (12a) fitted to the protecting annular member (11), a second encoder member (13) held between the protecting annular member (11) and the first encoder member (12), a seal annular member (14), and a seal member (15) which is vulcanized and bonded to the seal annular member (14) and has seal lips slidably contacting with the protecting annular member (11) and the encoder member (12).