A method and apparatus for compensating image skew and an electro-photographic image forming apparatus including the same are provided. Image skew of a toner image transferred onto a paper is compensated for by inclining a photosensitive medium onto which a light beam is scanned to be parallel to a scanning line of the light beam. A first inclination member including a first inclined surface facing upward and a second inclination member including a second inclined surface contacting and facing the first inclined surface are provided, wherein a position of a shaft of the photosensitive medium is adjusted by moving at least one of the first and second inclination members. Image skew of a toner image is sensed, and a photosensitive medium onto which a light beam is scanned is inclined to correspond to a scanning line skew of the light beam.