PURPOSE: To provide an X-ray lithography system in which workability and operational efficiency are enhanced by stopping fake out of SOR light in required beam line while sustaining operation of an SOR ring thereby allowing a predetermined work.

CONSTITUTION: An SOR ring is provided with a plurality of deflecting magnet section 6 and a beam duct 9 having a plurality of ports 8 for taking out SOR light from the deflecting magnet section in the tangential direction of electron orbit is interposed between the defelecting magnet section and a beam line 2. Each take-out port 8 of the beam duct is provided with a barrier 22 for selecting the SOR light taken out through respective ports depending on respective requirement and blocking irradiation onto the beam line side, and a drive mechanism 23 therefor.