In a bearing apparatus provided herein a hard steel shaft is an opposite shaft of an Al-Sn-Si based alloy plain bearing. Its wear resistance is enhanced. The bearing apparatus comprises a steel shaft having hardness of Hv 500 or more at least on a surface thereof, and a plain bearing. The plain bearing is formed of an aluminum alloy containing 2 to 10 mass% of Si, 8 to 18 mass% Sn, and the balance being Al and unavoidable impurities, wherein the volume of Sn phase is 50% or more of the volume of the Si particles( the average particle diameter of Si of the aluminum alloy is 4 to 10 µm). The aluminum alloy has a hardness of Hv 45 or more.