[en] The vacuum system of the PF-AR was improved for the upgrading of the ring as a synchrotron light source. All of beam chamber, vacuum device and control system were almost renewed. An existing lattice and magnets themselves are not changed. The new vacuum system has been designed and constructed in order to achieve the vacuum condition necessary for required beam lifetime and to enable increase the storage current. Titanium sublimation pumps and ion pumps of the considerable amount are equipped as main pumps in order to reinforce the pumping speed, and the copper is adopted as a main material of the chamber in order to cope with the thermal load and the radiation leakage. The system satisfactory started, and designed performance is successfully being achieved. (author)