When any defect occurs in an operation data group acquired by an operation data acquiring means 3, the defective data part is complemented by using complement data complemented by a defective data complementing means 6, and analyzed according to a failure diagnostic rule 5a by a failure diagnosing means 4. 運転データ取得手段3で取得された運転データ群に欠損がある場合、その欠損データ部分を欠損データ補完手段6で補完された補完データを用いて補完した上で故障診断手段4で故障診断ルール5aに従って解析する。 - 特許庁