A process for producing a heat-treated sintered iron alloy part, the process comprising: austenizing an iron-based sinter having a martensitic transformation initiation point (Ms point) of from 50.degree. to 350.degree. C., at a temperature not lower than the austenizing temperature (Ae1 point) of the sinter; quenching the austenized sinter at a cooling rate at which martensitic transformation occurs; and sizing or coining the quenched sinter at the time when the temperature of the sinter which is being quenched has reached the temperature range of from the Ms point to the Ae1 point.