音声対話による大規模知識ベース検索システム「音声版ダイアログナビ」について紹介する．音声対話システムにおいては，話し言葉特有の冗長性や，音声認識誤りに対処する必要がある．音声版ダイアログナビでは，検索に決定的な影響を与える箇所は検索を実行する前に確認し，結果として検索に影響を及ぼす箇所は検索結果の違いに基づいて効率的な確認を行う．The paper describes Speech Dialog Navigator, which can retrieve from large scale document with spoken dialog. Adequate confirmation is indispensable in spoken dialog systems to eliminate misunderstandings caused by speech recognition errors. Spoken language also inherently includes redundant expressions such as disfluency and out-of-domain phrases, which do not contribute to task achievement. The system can cope with these problems by making confirmation prior and posterior to the retrieval.