Provided is a cyan ink applicable to an ink set having four kinds of aqueous inks composed of the cyan ink, a magenta ink, a yellow ink, and a black ink each containing water; a water-insoluble coloring material; and plurality of water-soluble organic solvents including a good medium or good mediums for the water-insoluble coloring material and a poor medium or poor mediums for the water-insoluble coloring material. The content of the water-insoluble coloring material in the cyan ink is in a specific range, and the ratio B.sub.1/A.sub.1 between the good medium and the poor medium is also in a specific range. A water-soluble organic solvent showing the maximum Ka value out of respective Ka values of the plurality of water-soluble organic solvents is the poor medium. The ratio A/B between the good medium and the poor medium in an arbitrary aqueous ink in the ink set except the cyan ink and B.sub.1/A.sub.1 satisfy a specific relationship. The cyan ink provides an image having a sufficiently large area factor even with a small amount of ink droplets, and having a high image density, and is excellent in storage stability and bronzing resistance.