With total four lysimeters, having a decreased reaction rate of municipal solid waste (MSW) through the 1st study, the effects of foodwaste leachate (FWL) injection on the degradation of MSW and FWL were estimated for 533days. Average methane potential of FWL injected in lysimeters investigated through the Biochemical Methane Potential (BMP)test was 368.2 mL-CH4/g-VS. The amounts of methane generated in lysimeters injected simultaneously with FWL and leachate were higher than that of FWL injected each lysimeter. The pH levels of leachate generated in each lysimeter maintained a range of 7.2 ~ 8.1. CODCr concentrations were 1,640 ~ 2,275 mg/L initially, and were rising to 4,640 ~ 5,950 mg/L as increasing FWL injection amount. Whereafter those repeated fluctuation in a range of 2,400 ~ 5,600 mg/ L as methane productions in each lysimeter increase. BOD5/CODCr ratios were kept below 0.1 during the test period. Settlement analysis results of MSW in each lysimeter indicated that the simultaneous injections with FWL and leachate in each lysimeter promoted the degradation of not only FWL itself, but MSW. This became clear when the methane balance in lysimeter under rich-organic condition is established.