An extreme ultraviolet light generation apparatus includes: an optical base; and a chamber module replaceable from the optical base. The chamber module includes a chamber in which extreme ultraviolet light is generated, a condenser mirror disposed inside the chamber and configured to condense extreme ultraviolet light generated inside the chamber, a window configured to transmit, into the chamber, a laser beam introduced into the optical base, and having a function to seal up the chamber, and a laser beam condensation optical system configured to condense the laser beam having transmitted through the window.