An ink obtained by dissolving at least one specific dye in an aqueous medium, wherein the dyes contained in the ink all have a solubility of 15 g or more in 100 g of water at 25.degree. C. under atmospheric pressure; and an ink set formed from the ink. The dye is preferably a dye having an oxidation potential of 1.0 V (vs SCE) or more, more preferably a specific azo dye having a heterocyclic group of a specific structure or an aromatic group which is bound directly to an azo group, or a specific phthalocyanine dye having a water-soluble group as a substitunet. According to the present invention, an ink, specifically an inkjet ink, and an ink set, which can print an image without disorder or beading due to ejection failure and ensure excellent ejection stability and durability, is provided.