  We study the time delay between two relativistic images due to strong
gravitational lensing of the light rays caused by the Kerr and Kerr-Newman
black holes. The trajectories of the light rays are restricted on the
equatorial plane. Using the known form of the deflection angle in the strong
deflection limit (SDL) allows us to analytically develop the formalism for the
travel time of the light from the distant source winding around the black hole
several times and reaching the observer. We find that the black hole with
higher mass or with spin of the extreme black hole potentially have higher time
delay. The effect of the charge of the black hole enhances the time delay
between the images lying on the opposite side of the optical axis resulting
from the light rays when one light ray is in the direct orbit and the other is
in the retrograde orbit. In contrary, when both light rays travel along either
direct or retrograde orbits giving the images on the same side of the optical
axis, the charge effect reduces the time delay between them. We then examine
the time delay observations due to the galactic and supermassive black holes
respectively
