To provide a sliding bearing to improve load transfer capacity, fatigue strength and a pressure loading property as a ferrous metal mixed powder compact is connected to steel iron back surface metal simultaneously at the time of sintering and impregnated with lubricating oil to lengthen a grease non-lubricating period and easy to maintain and control, and its manufacturing method.

Steel iron back surface metal 81 and a ferrous sintered alloy layer 87 connected to the steel iron back surface metal and constituted of a 10-30 pts.wt. of copper and a remaining part of iron are contained. Thereafter, the steel iron back surface metal treated with copper plating is inserted into a form of a compacting device, metal mixed powder containing a 10-30 pts.wt. of copper, a less than 6.5 pts.wt. of graphite and a remaining part of iron is filled between a core and the steel iron back surface metal, an upper part pressure member is inserted on an upper end of the form, it is compacted by pressurizing it at 50-300 kgf/cm2, and the compact is maintained with the steel iron back surface metal for 3-25 min. at 1065-1095°C under specified neutral, reducing and inert gas atmosphere.