A relative version of Rickard's theorem is proved, namely, if ω is a quasi-Frobenius proper class of short sequences in an Abelian category <MATH>\Cal A</MATH>, then the ω-stable category of the category <MATH>\Cal A</MATH> is a quotient category of the relative bounded derived category Dbω(<MATH>\Cal A</MATH>). Bibliography: 20 titles.