An air feed device (1) for a fuel cell, having a shaft (2); a compressor wheel (4) fastened to one of the ends (5, 20) of the shaft (2), a bearing arrangement (6, 7, 8) arranged in a bearing housing (9) for mounting the shaft (2), and an electric motor (10) for driving the shaft (2), which electric motor is arranged in the bearing housing (9). The shaft (2) has two shaft bearing portions (11, 12) and a magnet portion (13) arranged between the shaft bearing portions (11, 12), forming the rotor of the electric motor (10). The shaft bearing portions (11, 12) and the magnet portion (13) are centered relative to one another by means of a centering arrangement (12A, 13F) which engages on an outer edge (A), the shaft bearing portions (11, 12) and the magnet portion (13) bearing in each case axially against one another.