Let A be a self-adjoint operator algebra of Hilbert space H,a be a*- endomorphism of A.If there exists a unit element e∈H such that lim_(→∞)〈α~n(a)h, h〉=〈ae,e〉for allα∈A and h∈H with‖h‖=1,then we sayαisσ-weak mixing with respect to A.In this paper,we establish a condition for an *-endomorphism to beσ-weak mixing.