An extreme ultraviolet light generation apparatus used in combination with a laser system, the apparatus may include: a chamber provided with at least one inlet port for introducing a laser beam outputted from the laser system into the chamber; a target supply unit provided to the chamber for supplying a target material to a predetermined region inside the chamber, where the target material is irradiated with the laser beam; at least one optical element disposed inside the chamber; a magnetic field generation unit for generating a magnetic field around the predetermined region; an ion collection unit disposed in a direction of a line of magnetic force of the magnetic field for collection an ion which is generated when the target material is irradiated with the laser beam and is flowing along the line of magnetic force; and a gas introduction unit for introducing an etching gas into the chamber.