The present invention provides: a reaction injection molding liquid mixture comprising a norbornene-based monomer, a metathesis polymerization catalyst that includes tungsten as a center metal, an activator, and an ether compound represented by a formula (1), wherein R1 to R4 are independently an alkyl group having 1 to 6 carbon atoms, the reaction injection molding liquid mixture comprising the activator and the ether compound in a molar ratio (ether compound/activator) of 0.7/1 to 30/1; a method for producing a reaction injection molded product comprising a reaction injection molding step that includes subjecting the reaction injection molding liquid mixture according to any one of claims 1 to 4 to bulk polymerization inside a mold; a reaction injection molded product obtained using the method for producing a reaction injection molded product. Consequently, the present invention provides: a reaction injection molding liquid mixture that makes it possible to obtain a reaction injection molded product that has an excellent surface (surface state) and exhibits excellent strength while preventing a situation in which the resin remains on the surface of the mold when the resin is removed from the mold, a method for producing a reaction injection molded product using the same, and a reaction injection molded product obtained using the method.