The present invention provides a stainless steel as a metal base material for a weight sensor substrate of an automobile airbag. The stainless steel sheet contains a high aluminiferous ferritic stainless steel containing, in mass, Al of 2.5 to 8%, C: 0.025% or less, N: 0.025% or less, the sum of C and N being 0.030% or less, and Nb: 0.05 to 0.5%, with the balance Fe and unavoidable impurities. Said stainless steel sheet may further contain, in mass, one or more of V: 0.05 to 0.4%, Ti: 0.02 to 0.2%, and Zr: 0.02 to 0.2%. The present invention controls the difference in the average linear expansion coefficient between said stainless steel sheet and crystallized glass for said weight sensor to less than 10% in the temperature range from 20° C. to 900° C. and thus to improve the adhesiveness of said stainless steel sheet with said crystallized glass.