A depth image generating apparatus includes a light source configured to emit light; an optical shutter provided on a path of the light reflected by an object and configured to modulate a waveform of the reflected light by changing a transmissivity of the optical shutter with respect to the reflected light; a driver configured to apply a driving voltage to the light source and a driving voltage to the optical shutter; a temperature measurer configured to measure a temperature of the optical shutter; a controller configured to control driving voltages; and a depth information obtainer configured to generate an image corresponding to the reflected light that passes through the optical shutter, extract a phase difference between a phase of the light emitted by the light source to the object and a phase of the reflected light, and obtain depth information regarding the object based on the phase difference.