An iron based powder mixture for powder metallurgy is provided which can produce a sintered material having by far higher machinability and sliding properties than conventional sintered materials, and also a sintered material containing alloy elements but having adaptability to sizing even after sintering; it comprises an atomized iron powder comprising S in a content of 0.03 to 0.30 wt %, Mn in a content of 0.05 to 0.40 wt % and the balance Fe and incidental impurities, to which is added one or more than one B-containing compound powder selected from boron nitride (BN), boric acid (H.sub.3 BO.sub.3), boron oxide (B.sub.2 O.sub.3) and the like in an amount of 0.001 to 0.3 wt % expressed as B, and incorporated with an MnS powder in an amount of 0.05 to 1.0 wt %, optionally alloyed partially with or prealloyed with Ni, Mo and Cu.