For KEK B-factory (KEKB), two rings with a circumference of 3016 m, mainly made of copper have been constructed. One ring stores a maximum of 2.6 A positron beam with the energy at 3.5 GeV, the other stores 1.1 A, 8 GeV electron beam. These stored currents far exceed those of existing electron storage rings. The inside of a beam duct is designed to minimize an effect of beam induced fields. A gap between flanges is filled using Helicoflex as a vacuum seal. Contact force of a RF finger in a bellows is assured by the use of a spring finger. Pumping slots are backed by crossing bars to prevent the penetration of beam induced fields. To obtain a pressure of 10(-7) Pa with beam, a pumping speed is designed to realize 0.1 m(3) s(-1) m(-1) assuming that the photodesorption coefficient reaches 10(-6) molecules/photon. The NEG strip is used as a main pump element. Chemical polishing is applied to clean the extruded surface of copper chambers. Almost all chambers are baked before installation. Only ion pumps are baked in situ. From beginning to end, a completely oil free pumping system is used. The photodesorption coefficient at the start of the commissioning was slightly higher than expected, but the decrease of the coefficient is as expected on the whole. There is no trouble on the RF contact for bellows.