the present invention discloses an apparatus and a method for diagnosing abnormal conditions , that quantitatively considers acquisition difficulties between abnormal symptoms provided on a computer screen and quantifies acquisition difficulties of the abnormal symptoms through distinctiveness of measuring devices to exactly diagnose the abnormal conditions even under an improved control environment , making it possible for a user to rapidly and easily diagnose the abnormal conditions that may be generated from a complicated device . with the present invention , the abnormal conditions are diagnosed using the sequential diagnosis technique and the boolean logic between the abnormal symptoms , making it possible to effectively diagnose the abnormal conditions even under masking effects that may be generated between the abnormal symptoms .