To provide a resin for an offset ink, whereby an equal or higher level of properties are obtained in comparison with those obtained from a conventional rosin-modified resin, without using an alkylphenol and formaldehyde.

The resin for an offset ink is obtained by reacting (a) a polymerized rosin, (b) at least one of a vegetable oil, a polymerized vegetable oil, a vegetable oil fatty acid and other higher fatty acids, (c) an unsaturated dibasic acid, (d) a polyhydric alcohol and (e) a surfactant, and has 120-220°C softening point and 5,000-300,000 weight average molecular weight.