The aqueous ink for ink jet contains a resin particle dyed with a fluorescent dye, and a water-soluble resin. The fluorescent dye contains a fluorescence-emitting dye selected from the group consisting of basic dye, disperse dye and oil-soluble dye, the resin particle has a core portion that contains an aromatic group-containing unit and cyano group-containing unit, and a shell portion that contains an aromatic group-containing unit, an anionic group-containing unit and a crosslinking agent-derived unit, but free of cyano group-containing unit, percentage (% by mass) of the crosslinking agent-derived unit in the shell portion is 30% by mass or more to 80% by mass or less, the water-soluble resin having an aromatic group-containing unit and an anionic group-containing unit, and the water-soluble resin having an acid value of 100 mgKOH/g or more to 180 mgKOH/g or less.