An apparatus for generating a lip sync image according to a disclosed embodiment has one or more processors and a memory which stores one or more programs executed by the one or more processors. The apparatus includes a first artificial neural network model configured to generate an utterance synthesis image by using a person background image and an utterance audio signal corresponding to the person background image as an input, and generate a silence synthesis image by using only the person background image as an input, and a second artificial neural network model configured to output, from a preset utterance maintenance image and the first artificial neural network model, classification values for the preset utterance maintenance image and the silence synthesis image by using the silence synthesis image as an input.