Set of ink and reaction liquid, and image forming method

A set of an ink and a reaction liquid for ink jet, the set having a combination of an ink comprising a pigment and a water-soluble resin and a reaction liquid containing no coloring material but comprising a surfactant and having buffering ability in an acid region, wherein

• the pigment in the ink comprises a self-dispersible pigment to a particle surface of which an anionic group is bonded directly or through another atomic group, and the weight-average molecular weight of a functional group bonded to the surface of the pigment particle is 1,000 or less,
• the water-soluble resin comprises a copolymer having a unit derived from (meth)acrylic acid,
• the surfactant in the reaction liquid comprises an ethylene oxide adduct of a higher alcohol selected from the group consisting of a linear primary alcohol, a linear secondary alcohol and an isoalkyl alcohol and has a HLB value of 13.0 or more as determined by the Griffin method, and
• the content (% by mass) of the surfactant in the reaction liquid is 0.20 times or more in terms of mass ratio as much as the total content (% by mass) of the pigment and the water-soluble resin in the ink.