The electrical resistivity of the austenite and martensite mixture produced in both quench or sub-zero (an abridged term of QS is used hereafter) treatment and tensile plastic deformation is shown to agree, well with the logarithmic mixture rule, varying its deviation coefficient, κ, in between plus and minus unities. The variation of κ is discussed in terms of the amount of plastic deformation and the dislocation motions in the austenite matrix of the mixture. The volume fraction of martensite in the mixture, produced in the latter, is examined to be predicted by the modified relation of the velocity of an autocatalytic chemical reaction (abbreviated as VACR) as well as the relation of the shear band intersection mechanism (abbreviated as SBIM). Here the former is employed to express the experimental results simply because of two coefficients needed to be determined and because of the fact that this steel transforms more or less in a burst type. The logarithmic mixture rule and the modified relation of VACR lead to an expression that the electrical resistivity-change of the mixture is a function of plastic strain, and the experimental variations are consistent with this.