An organometallic compound obtained by mixing following (a), (b) and (c): (a) a neutral organopalladium complex that has a palladium atom and two organic ligands each having at least three carbon atoms participating in a bond to the palladium atom; (b) an organophosphorus compound having one phosphorus atom; and (c) a salt comprising: an anion having no unshared electron pair in a central atom; and a counter-cation. And a process for producing a norbornene compound polymer, the process comprising: subjecting at least one norbornene compound represented by formula (A) as defined in the specification to polymerization reaction in a presence of an organometallic complex catalyst produced by mixing compound (a) and compound (d) described in the specification.