Users often encounter unreliable information on the Web, but there is no system to check the credibility easily and efficiently. In this paper, we propose a system to search useful information for checking the credibility of uncertain facts. The objective of our system is to help users to efficiently judge the credibility by comparing other facts related to the input uncertain fact without checking a lot of Web pages for comparison. For this purpose, the system collects comparative facts for the input fact and important aspect for comparing them from the Web and estimates the validity of each fact.