A video projection apparatus includes: a light source; an optical deflector having a mirror for reflecting light to project a view field, an actuator for rocking the mirror with an axis of the mirror and a sensor provided in the vicinity of the actuator; and a control unit. The control unit generates a sine-wave voltage applied to the actuator and a cosine-wave voltage; calculates a first convolution between the sine-wave voltage and a sense voltage from the sensor; calculates a second convolution between the cosine-wave voltage and the sense voltage; converts an orthogonal coordinate formed by the first convolution and the second convolution into a polar coordinate formed by a radius component and an angle component; and sweeps the frequency of the first and second voltages so that the frequency is defined as a resonant frequency when the radius component is maximum.