An iron-base sintered part having high density and totally enhanced strength, toughness and abrasion resistance, a manufacturing method of the iron-base sintered part, and an actuator are disclosed. The iron-base sintered part is formed by an iron-nickel-molybdenum-carbon-based sintered alloy, has density of 7.25 g/cm3 or more, and has a carburization quenched structure. A method for manufacturing the iron-base sintered part includes a molding process of charging a raw mixture powder of an iron-nickel-molybdenum-based metal powder and a carbon-based powder into a cavity of a molding die and compressing the raw powder in the cavity to form a consolidation body, a sintering process of sintering the consolidation body at a sintering temperature to form a sintered alloy, and a carburization quenching process of heating the sintered alloy in a carburization atmosphere and quenching the heated alloy.