A vane air motor is disclosed which is configured to prevent grease in a radial bearing from leaking into a rotor chamber. The vane air motor has a motor housing (20) having a rotor chamber, a rotor (22) with vanes (24) disposed in the rotor chamber, a first end wall (16) of the motor housing equipped with a radial bearing (50) rotatably supporting a support shaft portion (28) of the rotor, and a casing contiguously joined to the motor housing to form a compressed air supply chamber (44) together with the first end wall to supply compressed air into the rotor chamber through an air supply hole (46) formed in the first end wall. The first end wall has communication means (16-5, 16-6 and 16-7) for supplying compressed air from the compressed air supply chamber to the side of the first radial bearing closer to the rotor.