Intensification of the livestock industry has become environmentally problematic due to the uncontrolled treatment of large amounts of watery manure. One solution is the adoption of biogas plants (BGPs). Hokkaido, Japan, has significant potential for BGP adoption, however, the large financial investments and lack of grid space for selling electricity are barriers. We investigated the relationship between the willingness of farmers to adopt BGPs and their current farming situations. Using a questionnaire survey and multivariate analyses, the results showed that large-scale farmers, particularly those with more than 100 mature cows, were clearly willing to adopt BGPs and expand their businesses in the future, while farmers who planned to downsize their businesses did not exhibit strong willingness to adopt BGPs. In addition, farmers willing to adopt BGPs thought the plants would help solve problems with manure treatment. BGPs might be more accepted by dairy farmers if there were greater incentives for installation given the role BGPs can play in providing stable energy and revitalizing local economies.