An oil feeding device for plain bearings supporting a crankshaft connected to an orbital scroll member in a scroll fluid apparatus, including axially extending oil flow passages formed on the outer peripheral surface of the crankshaft at portions journaled by the plain bearings but displaced from the lines of action of lateral loads caused by fluid pressure in the sealed space between two scroll members, thereby generating bearing oil film reactions commensurate with the lateral loads, so as to produce an optimum oil film pressure distribution for the bearings at all times.