Provided is a pretreatment liquid for aqueous pigment inkjet printing which excels in adhesion to non-permeable substrates such as film substrates and which can provide printed material having good printed image quality with little mixed color bleeding and color unevenness. Also provided is an ink set including the pretreatment liquid and an aqueous pigment inkjet ink. The pretreatment liquid for aqueous pigment inkjet ink printing comprises polyolefin resin particles (A), a flocculant (B), and water. The softening temperature of the polyolefin resin particles (A) is from 50 to 100° C., and the flocculant (B) contains at least one type of substance selected from metal salts and cationic polymer compounds.