<p>An ink for marking with which the outer surface of an article comprising a polyvinyl chloride resin can be marked by coloring without forming a coating film from a film-forming resin and which has excellent recognizability after this marking. The ink for marking comprises an organic solvent and an oil-soluble dye, wherein the absolute value of the difference in solubility parameter between any two of the solvent, the dye, and the polyvinyl chloride resin constituting the article to be marked with the marking ink should be a certain value or smaller.</p>
