A graft polymer containing a cyclic structure comprised of a polymer containing a cyclic structure graft-modified with an unsaturated compound containing a polar group, having a graft ratio of 10 to 150 mol %, having a weight average molecular weight of 1,000 to 1,000,000, and having a gel content of not more than 0.1 wt % or having a ratio (Ha/La) of high molecular weight side area (Ha) and low molecular weight side area (La) divided by a vertical line suspended from a peak top of a differentiated elution profile measured by gel permeation chromatography to a baseline of not more than 1.6, a method of production of the same, and a curable composition containing that graft polymer containing a cyclic structure and a curing agent.