A bearing device where a sliding bearing rotatably supporting a shaft is molded with an inexpensive sintered material, three asymmetrical circular arc-shaped radial bearings are formed in the inner peripheral surface of the shaft, taper land-shaped thrust bearings are formed in the opposite end surfaces of the radial bearing surface, T-shaped bubble removing means which is constituted by axial and radial flow passages formed in the shaft opposed to the radial bearing is provided, and magnetic fluid is used as a lubricant. A magnetic disk unit using the bearing device is also disclosed.