A method for producing an olefin block polymer, the method including: polymerizing olefins using a polymerization catalyst (X) and an organometallic compound (C) containing an atom of any of Groups 2, 12, and 13 of the periodic table of the elements, the organometallic compound (C) excluding an activating co-catalyst agent (B), wherein the polymerization catalyst (X) is formed by bringing a transition metal compound (A) into contact with the activating co-catalyst agent (B), the transition metal compound (A) is represented by the following general formula (1), and the activating co-catalyst agent (B) is selected from among an organoaluminumoxy compound (B-1), an organoboron compound (B-2), a zinc co-catalyst component (B-3), and ion-exchange layered silicate (B-4).