A method of generating a depth image includes irradiating an object with a light which is generated from a light source, acquiring a plurality of phase difference signals which have different phase differences from one another, by sensing a reflection light reflected from the object, generating a first depth image based on the plurality of phase difference signals, generating a second depth image based on phase difference signals in which a motion artifact has not occurred, among the plurality of phase difference signals, generating a third depth image by combining the first depth image and the second depth image.