An optical scanning endoscope apparatus includes: an illumination optical fiber that emits light from a tip part oscillatably supported an actuator that drives the tip part of the illumination optical fiber and a signal generator that generates, with respect to the actuator, a drive signal for causing the tip part of the illumination optical fiber to spiral scan. The signal generator generates the drive signal which includes: an amplitude expansion period for expanding the amplitude of the drive signal of the fiber from substantially 0 to a maximum value and an amplitude contraction period for contracting the amplitude of the drive signal from the maximum value to substantially 0, the drive signal having an envelope that smoothly continues, with a gradient of substantially 0, across a border between the periods, with the longer one of the periods being defined as an effective scanning period.
