A chamber device that is used with at least one laser beam generating device, comprising: a chamber provided with at least one incident port for introducing at least one laser beam, the laser beam being emitted from the at least one laser beam generating device, to an inside thereof; a target supply unit provided to the chamber and supplies a target material to a predetermined region in the chamber; a laser focusing optical system (15a, 15b) configured to focus the at least one laser beam in the predetermined region; and an optical element configured to correct light intensity distribution of a beam section, in the predetermined region, of the at least one laser beam, wherein the optical element is configured to correct the light intensity distribution so that the light intensity distribution of the beam section, in the predetermined region, of the at least one laser beam has predetermined evenness in the predetermined region of the beam section, the at least one laser beam having predetermined evenness when a value of variation C shown below be equal to or less than 20(%); C = Imax − Imin / Imax − Imin × 100 %, Imax: the highest light intensity in a predetermined region in the section orthogonal to the beam axis of a laser beam, Imin: the lowest light intensity in the predetermined region in the section orthogonal to the beam axis of a laser beam; characterized in that a minimum value of a dimension of the predetermined region in a direction orthogonal to the traveling direction of the laser beam is equal to or larger than a value obtained by adding a range of variation of a position of the target material in the predetermined region to a maximum value of a dimension in the orthogonal direction. a chamber provided with at least one incident port for introducing at least one laser beam, the laser beam being emitted from the at least one laser beam generating device, to an inside thereof; a target supply unit provided to the chamber and supplies a target material to a predetermined region in the chamber; a laser focusing optical system (15a, 15b) configured to focus the at least one laser beam in the predetermined region; and an optical element configured to correct light intensity distribution of a beam section, in the predetermined region, of the at least one laser beam, wherein the optical element is configured to correct the light intensity distribution so that the light intensity distribution of the beam section, in the predetermined region, of the at least one laser beam has predetermined evenness in the predetermined region of the beam section, the at least one laser beam having predetermined evenness when a value of variation C shown below be equal to or less than 20(%); C = Imax − Imin / Imax − Imin × 100 %, Imax: the highest light intensity in a predetermined region in the section orthogonal to the beam axis of a laser beam, Imin: the lowest light intensity in the predetermined region in the section orthogonal to the beam axis of a laser beam; characterized in that Imax: the highest light intensity in a predetermined region in the section orthogonal to the beam axis of a laser beam, Imin: the lowest light intensity in the predetermined region in the section orthogonal to the beam axis of a laser beam; a minimum value of a dimension of the predetermined region in a direction orthogonal to the traveling direction of the laser beam is equal to or larger than a value obtained by adding a range of variation of a position of the target material in the predetermined region to a maximum value of a dimension in the orthogonal direction.