Sintered Cr steels containing 1 and 3 mass%Cr were prepared from mixtures of atomized Fe-Cr alloy powder and graphite powder, by compacting and sintering at 1523 K for 3.6 ks in vacuum. Specimens were nitrided at 773 K for 3.6 ks in an ammonia gas atmosphere.The properties of the nitrided layer were investigated by electron probe microanalysis, transmission electron microscopy, X-ray diffraction and microvickers hardness testing etc, and the wear characteristics were studied by Ohgoshi type micro-wear testing without lubricant.Results obtained are summarized as follows.(1) Compound layers were formed not only on the surface but on the inner surface of pores and at grain boundaries connecting with pores. It was found by X-ray diffraction that these compounds were ε-Fe2.3N phases.(2) Fine precipitates were observed in the diffusion zones of sintered 1 and 3 mass%Cr steels by transmission electron microscopy, and were identified with CrN particles by electron diffraction.(3) By nitriding, the wear resistance of the sintered Cr steel was improved remarkably. But the wear resistance was aggravated by spalling of the compound layer formed on the surface, therefore, it is desirable to remove the surface compound layer, in order to have the good wear resistance.(4) In case of removing the surface compound layer, the wear rate of the nitrided specimen of the sintered 1 mass%Cr steel was nearly equivalent to that of the sintered 3 mass%Cr steel, so it is considered that the Cr content of the sintered Cr steel for nitriding with an ammonia gas must be about 1 mass%.