  We study both experimentally and theoretically the descending motion due to
gravity of a fluid drop surrounded by another immiscible fluid in a confined
space between two parallel plates, i.e., in the Hele-Shaw cell. As a result, we
show a new scaling regime of a nonlinear drag friction in viscous liquid that
replaces the well-known Stokes' drag friction through a clear collapse of
experimental data thanks to the scaling law. In the novel regime, the
dissipation in the liquid thin film formed between the drop and cell walls
governs the dynamics. The crossover of this scaling regime to another scaling
regime in which the dissipation inside the droplet is dominant is clearly
demonstrated and a phase diagram separating these scaling regimes is presented.
