Disclosed herein is a vehicle headlight equipped with a gas-discharge lamp, which is designed such that a high beam mode or a low beam mode is selectively operated by controlling a position of the gas-discharge lamp using a magnetic force, thus making the interior construction of the headlight compact, in addition to the prevention of frequent malfunction of the headlight. The headlight is provided with a lamp control means controlling a position of a bobbin in a housing to selectively operate the low beam mode or the high beam mode. The lamp control means includes a return spring provided in the housing to elastically bias the bobbin forward. A magnet assembly is installed in a rear portion of the housing in such a way as to be adjacent to a rear end of the bobbin. A solenoid is wound around a rear portion of the bobbin and cooperates with the magnet assembly to move the bobbin and a bulb rearward when electric power is applied.