Sintered steel contains numerous residual pores, and shows some characteristics of mechanical behavior different from those of ordinary metallic materials. Specimens of sintered steel with carbon content of 0.7%, and two different densities, 6.2g/cc and 6.7g/cc respectively, were examined with respect to their elastic moduli.The results obtained are summarized as follows;(1) The specimens showed a clear yield point and in the stress above the yield stress the elastic modulus decreased with increasing stress.In tension, the elastic moduli decreased to 80∼90% of original value just before failing in both specimens.(2) To explain the mechanism of the decrease of elastic moduli, the present author proposed a new element of mechanical model named the“breaker”. The breaker acts as a rigid body until the stress reaches a certain point, where it breaks off and after that point, it can not support any load.(3) By assuming a mechanical model in which the breaker elements of various strengths are distributed and break off continuously with increasing stress, the elastic moduli VS stress relation of sintered steel can be described.(4) In the actual fracture process of sintered steel, the breaking of the breaker element seems to correspond with the initiation and propagation of microscopic cracks and local failures in the vicinity of residual pores.