An image forming pretreatment liquid includes a cationic polymer and/or an organic acid of 0.5% by mass or more and 8% by mass or less relative to a total mass of the image forming pretreatment liquid. When the image forming pretreatment liquid includes the organic acid, a lower limit of a content of the organic acid in the pretreatment liquid is preferably 0.7% by mass or more relative to the total mass of the image forming pretreatment liquid. When the image forming pretreatment liquid includes the cationic polymer, a content of the cationic polymer in the pretreatment liquid is preferably 2% by mass or more and 10% by mass or less relative to a total mass of a nonvolatile content of the image forming pretreatment liquid.

An ink set contains a pretreatment solution and an ink composition, wherein the pretreatment solution contains an organic acid with a boiling point of 120 C. or lower at 1 atmospheric pressure, and the ink composition contains A to E below: (A) a white pigment; (B) an alkali-soluble resin being an acrylic-based copolymer resin with an acid value of 200 mgKOH/g or higher that also contains a monomer having carboxyl groups and a hydrophobic group-containing monomer as monomer components, amounting to a content of 1.0 to 3.0% by mass in the ink composition; (C) a water-dispersible resin with a glass transition temperature of 25 C. to 10 C.; (D) a silicone-based surfactant; (E) water. The ink set that can provide a printed matter (fabric) offering excellent abrasion resistance of the printed text and images, as well as good washing fastness and tackiness (non-sticking) of the printed face.