An extreme ultraviolet light generation system according to one aspect of the present disclosure includes: a pulse laser apparatus configured to output a pulse laser beam, the pulse laser beam being supplied to a predetermined region in a chamber in which plasma containing extreme ultraviolet light is to be generated; a sensor configured to detect a beam size of the pulse laser beam; an actuator configured to change the beam size; and a controller. The controller performs, based on a first algorithm, first control that controls the actuator by a first control amount in a beam size minifying direction when the beam size has exceeded a first upper limit threshold in one burst duration, and then performs, based on a second algorithm, second control that controls the actuator by a second control amount smaller than the first control amount so that the beam size becomes closer to a target value.