There are provided (1) a process for producing a compound, which comprises the step of contacting a compound (A) defined by the formula, M.sup.1L.sup.1.sub.3, a compound (B) defined by the formula, R.sup.1.sub.t-1TH, and a compound (C) defined by the formula, R.sup.2.sub.t-2TH.sub.2; (2) a catalyst component for addition polymerization, which comprises a compound produced by said process; (3) a process for producing a polymerization catalyst, which comprises the step of contacting said catalyst component with a transition metal compound and an optional organoaluminum compound; and (4) a process for producing an addition polymer, which comprises the step of addition polymerizing an addition polymerizable monomer in the presence of a catalyst produced by said process.