A biogas upgrading process was developed to achieve both high CH4 concentration and high CH4 recovery from biogas. First, we built process that can achieve both 95% CH4 concentration and 98% CH4 recovery by using DDR-type zeolite membranes with reduced pressure on the permeate side. Second, we showed that both 98% CH4 concentration and 98% CH4 recovery can be achieved by using a process combining a DDR-type zeolite membrane and a polyimide hollow fiber membrane. Finally, we clarified that this biogas upgrading system has long-term stability. The results show that a membrane separation system using a DDR-type zeolite membrane can be operated with lower environmental-impact and higher CH4 recovery than other biogas upgrading technologies.