An apparatus for detecting abnormal vibrations of a rotor, the apparatus comprising: a vibration information receiver configured to receive at least one type of information among vibration information regarding more than one dimensions distinguishing locations and directions of the rotor and rotor rotation information including a number of rotations of the rotor; characterized in that the apparatus further comprises: a multivariate management index calculator configured to calculate multivariate management indexes including a Hotelling's T-squared value and an upper control limit regarding the vibration information regarding the more than one dimensions; and an operation index extractor configured to determine an abnormality in vibration characteristics of the rotor when the Hotelling's T-squared value is greater than the upper control limit and configured to extract an operation index causing the abnormality in the vibration characteristics of the rotor from one or more operation indexes by using a residual magnitude between a Hotelling's T-squared value when there are all operation indexes among the one or more operation indexes included in a full learning model describing a relation between the operation indexes and the Hotelling's T-squared value, and a Hotelling's T-squared value when there are only the remaining operation indexes except for an operation index on which a contribution measurement is to be performed included in a reduced learning model describing a relation between the operation indexes and the Hotelling's T-squared value. a vibration information receiver configured to receive at least one type of information among vibration information regarding more than one dimensions distinguishing locations and directions of the rotor and rotor rotation information including a number of rotations of the rotor; characterized in that the apparatus further comprises: a multivariate management index calculator configured to calculate multivariate management indexes including a Hotelling's T-squared value and an upper control limit regarding the vibration information regarding the more than one dimensions; and an operation index extractor configured to determine an abnormality in vibration characteristics of the rotor when the Hotelling's T-squared value is greater than the upper control limit and configured to extract an operation index causing the abnormality in the vibration characteristics of the rotor from one or more operation indexes by using a residual magnitude between a Hotelling's T-squared value when there are all operation indexes among the one or more operation indexes included in a full learning model describing a relation between the operation indexes and the Hotelling's T-squared value, and a Hotelling's T-squared value when there are only the remaining operation indexes except for an operation index on which a contribution measurement is to be performed included in a reduced learning model describing a relation between the operation indexes and the Hotelling's T-squared value. a multivariate management index calculator configured to calculate multivariate management indexes including a Hotelling's T-squared value and an upper control limit regarding the vibration information regarding the more than one dimensions; and an operation index extractor configured to determine an abnormality in vibration characteristics of the rotor when the Hotelling's T-squared value is greater than the upper control limit and configured to extract an operation index causing the abnormality in the vibration characteristics of the rotor from one or more operation indexes by using a residual magnitude between a Hotelling's T-squared value when there are all operation indexes among the one or more operation indexes included in a full learning model describing a relation between the operation indexes and the Hotelling's T-squared value, and a Hotelling's T-squared value when there are only the remaining operation indexes except for an operation index on which a contribution measurement is to be performed included in a reduced learning model describing a relation between the operation indexes and the Hotelling's T-squared value.