Abstract: A method of producing an ink cured product having a step of printing an active energy beam-curable ink comprising a monomer having an ethylenic double bond and a photopolymerization initiator onto a substrate, and then curing the active energy beam-curable ink with an active energy beam, wherein the monomer having an ethylenic double bond comprises an acrylate monomer having a molecular weight of 330 or less and containing 1 to 3 acryloyl groups, the photopolymerization initiator comprises three or more types of compounds selected from the group consisting of (A1) ?-aminoalkylphenone compounds, (A2) acylphosphine oxide compounds, (B1) thioxanthone compounds and (B2) benzophenone compounds, and the substrate is either a paper having a high degree of smoothness or a plastic film.