A process of producing a urethane (meth)acrylate monomer having a low acid value and a low content of a hardly soluble high-molecular weight impurity which is crosslinked high-dimensionally, comprising the steps of: (1) contacting a first solution containing a urethane (meth)acrylate monomer having an acid value of more than 0.2 mgKOH/g and an organic solvent to a water-containing adsorbent capable of adsorbing an acid component to obtain a second solution containing a urethane (meth)acrylate monomer having an acid value of not more than 0.2 mgKOH/g, the organic solvent and more than 5,000 ppm (mass) of water based on the urethane (meth)acrylate monomer; (2) contacting the second solution to a dehydrating agent to obtain a third solution containing not more than 5,000 ppm (mass) of water based on the urethane (meth)acrylate monomer; and (3) removing the organic solvent from the third solution.