A scanning endoscope apparatus is provided that includes: an endoscope having a light guide portion configured to guide and emit an illuminating light for illuminating a subject, and an actuator configured to oscillate the light guide portion; a storage portion configured to store a resonance frequency at a time when 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 signals that are applied to the actuator; and a determination portion configured to compare a frequency of a signal which is smallest in a case where the actuator is taken as a load with the resonance frequency stored in the storage portion to determine whether or not the endoscope is abnormal.