We propose a public debate support system through iterative alternation of face-to-face meetings and Web-based debates. Web-based facilitation of public debates is suitable for complementary question and answering when the debate in face-to-face meetings is insufficient due to time restriction. Since transcripts of public meetings tend to be lengthy and specialized, sharing public concerns among citizens and stakeholders requires much time and effort. To solve this problem, we propose two approaches. First, supporting the sharing of public concerns with structuration of public debate based on rhetorical structure theory (RST). It enables a user to manually specify his/her intention of a question, e.g., the question requires more evidence. An intention tag is effective for facilitating public debate. Second, supporting reading with visualization of topic transition, using our developed SalienceGraph. Moreover SalienceGraph retrieves passages related to a transient topic from past meeting records or documents. These approaches support citizens and stakeholders in finding, tracking, and sharing public concerns.