An induction heating apparatus for heating in depth the surface of the rolls of a rolling mill including an inductor fed by an alternating current of low or medium frequency and a device permitting the rolls to rotate around their axes. The inductor comprises two end frames and two lateral conductors connecting the two end frames so as to form an inductor having two longitudinal symmetry planes which are perpendicular with respect to each other. There is also provided a device for regulating the device permitting to rotate the rolls around their axes, such regulating device being arranged so as to permit the axes of the rolls to coincide with the intersection line of the two longitudinal symmetry planes.