The present invention relates to a stimuli-responsive composition that contains a polymer, a solvent and a substance having a predetermined function. One embodiment of the composition contains a block polymer, a solvent and a substance having a predetermined function. Preferably, the solvent in the composition is water; and the polymer in the composition has a polyvinyl ether structure. The composition has superior dispersion stability. The present invention also relates to an ink composition containing the composition, an image-forming method and an image-forming apparatus using the ink composition, and a recording medium having the composition.