The effects of microstructural factors and sintering conditions on mechanical properties of the sintered SUS304L stainless steel compacts made by powder injection molding were investigated. The specimen were made of water-atomized (W) and gas-atomized (G) powders which were blended with a polyamide binder system. The tensile strength and elongation of the sintered compacts were equivalent to those of the wrought steel. The tensile strength and elongation of the compact sintered at 1673 K were 520MPa and 57% respectively. The grain growth in the W-powder compact and the G-powder compact was governed by the cubic low. The restrictive force of precipitates in the W-powder compact at the grain boundary was stronger than that of pores in the G powder compact. The proof stress of the compact followed the Hall-Pecth relationship.