This paper examines the political underrepresentation of people with disabilities in the Japanese Diet and the conditions that allow their participation in the body. The paper addresses the following three research questions: (a) how are people with disabilities represented in contemporary Japan and the EU member states, and what are the differences between them?; (b) why have people with disabilities been underrepresented in Japan? and (c) how do candidates with disabilities but lacking typical political careers become members of the Diet? This paper further discusses the electoral system, political parties’ attitudes toward people with disabilities, social and community participation of people with disabilities, and political culture as factors that affect minority groups’ participation in the Japanese Diet. Key findings: (a) a comparison with EU member states shows that the underrepresentation of people with disabilities in parliamentary bodies is a common issue; (b) people with disabilities are less involved in traditional political communities and society in general, which hampers their participation in the parliament and (c) in the immediate postwar period disabled Diet members were mainly wounded people with typical political careers, but from the 1990s onwards disabled people without typical political careers became Diet members. Moreover, the proportional electoral system and political parties’ stronger commitment to include candidates with disabilities facilitated the increase in disabled membership.