A compact vortex-stream gas-liquid separator, and a gas-liquid separation system employing it, offers high gas-liquid separation performance with minimal pressure loss. A substantially cylindrical casing (10) is arranged with its axis lying horizontally. The casing has a fluid passage (1) formed therein, has a fluid inlet (2) provided at one end, and has a gas outlet (3) and a liquid outlet (4) provided at the other end so as to constitute as a whole a vortex-stream gas-liquid separator (9). The fluid inlet is arranged along a line tangential to the casing so that the gas-liquid two-phase fluid passes through the fluid passage in the form of a vortex stream. The gas outlet is arranged so as to be coaxial with the casing. This vortex-stream gas-liquid separator and the gas-liquid separation system (30) employing it are used in a clothes dryer or air conditioner to remove water droplets from air.