Process for producing cured object, cured object, and layered product including said cured object

Provided is a cured object which is excellent in terms of heat resistance, crack resistance (or thermal shock resistance), adhesiveness to adherends, and adhesive property. The cured object according to the present invention is obtained by subjecting a curable composition containing a polymerizable-group-containing compound to a heat treatment in which the curing temperature is changed in stages so that the composition has a degree of cure of 85% or less at the time when the first stage of the heat treatment is completed and the degree of cure is elevated to above 85% by the second and subsequent stages of the heat treatment. The polymerizable-group-containing compound is preferably a compound having a group selected from the group consisting of epoxy, oxetanyl, vinyl ether, and vinylphenyl groups, and an epoxy-modified polyorganosilsesquioxane is especially preferred.