The effect of heat treatment conditions on the microstructure and mechanical properties of SUS630 compacts made by metal injection molding were investigated. The compacts were made by injecting the mixtures of gasatomized SUS630 powder and polyamide binder into a metallic mold. The compacts were debound in air at 593K for 7.2ks, and sintered in vacuum at 1573K for 7.2ks. The specimens were aged at various temperatures between 753K and 893K after solution treatment. The microstructures of the heat treated compacts consisted of martensite and δ-ferrite. Both proof stress and tensile strength tended to become smaller with raising the aging temperature. The maximum values of proof stress and tensile strength of the heat treated compacts were as high as 1190MPa and 1330MPa respectively, and these values were equivalent to those of wrought steels. Charpy impact value increased with increasing the aging temperature. Charpy impact value of the compacts was smaller than that of wrought steel.