An ink including a self-dispersible pigment, acrylic resin particles, a water-soluble organic solvent, and water. The self-dispersible pigment includes a phosphonic-acid-based self-dispersible pigment having a phosphonic acid group bonded directly or via another atomic group to a surface of particles of the pigment. The acrylic resin particles are formed of an acrylic resin containing a constituent unit derived from an ester-bond-containing monomer. The content of the constituent unit derived from the ester-bond-containing monomer in the acrylic resin is 60 mol % or more based on the total of the acrylic resin.