A scanning endoscope apparatus is provided that includes: a scanning endoscope having a light guide portion for guiding an illuminating light for illuminating a subject and emitting the illuminating light from an emitting end, and an actuator configured to oscillate the emitting end of the light guide portion in accordance with a voltage of a signal applied to the actuator in order to scan the illuminating light over the subject; a storage portion configured to store in advance, as information regarding a frequency of the signal applied to the actuator, information regarding a resonance frequency at a time when the emitting end of the light guide portion is caused to oscillate in a resonant state; an application portion configured to sequentially apply a plurality of signals having different frequencies to the actuator; a signal monitoring portion configured to monitor the plurality of signals that are sequentially applied to the actuator; and a determination portion configured to compare information regarding a frequency of a signal at a time when impedance is smallest in a case where the actuator is taken as a load among the plurality of signals monitored by the signal monitoring portion with the information regarding the resonance frequency stored in the storage portion to determine whether or not the scanning endoscope is abnormal.