Although Web search engines have become information gateways to the Internet, for queries containing technical terms, search results often contain pages that are difficult to be understood by nonexpert users. Therefore, re-ranking search results in a descending order of their comprehensibility should be effective for non-expert users. In our approach, the comprehensibility of Web pages is estimated considering both the document readability and the difficulty of technical terms in the domain of search queries. To extract technical terms, we exploit the domain knowledge extracted from Wikipedia. Our proposed method can be applied to general Web search engines as Wikipedia includes nearly every field of human knowledge. We demonstrate the usefulness of our approach by user experiments. Categories and Subject Descriptors H.3.3 [Information Search and Retrieval]: Retrieval models General Terms Algorithm Keywords Web search, comprehensibility, Wikipedia mining, readability