Micellar shape change in amphiphilic solution after sudden change in the solvophilic interaction is studied by molecular dynamics simulations of coarse-grained, rigid amphiphiles. Our simulations demonstrate that, after sudden increase in intensity of the solvophilicity, the disc micelle transforms into cylindrical or spherical micelles immediately. In contrast, spherical micelles coalesce into a disc micelle in a stepwise manner after sudden decrease in intensity of the solvophilicity.