A belt skew correcting device corrects a deviation of an endless belt which is supported by a plurality of rollers and which is driven to rotate around the plurality of rollers. An inclined sectional surface of a dislocating member is guided by an inclined sectional surface of a guide member in accordance with a following movement of a following member, so that a rotational shaft of one roller is given a tilt corresponding to an amount of the movement of the endless belt along the rotational shaft, and thereby the one roller can be tiled.