  We investigate the characteristic of microlensing signals of Earth-like moons
orbiting ice-giant planets. From this, we find that non-negligible satellite
signals occur when the planet-moon separation is similar to or greater than the
Einstein radius of the planet. We find that the satellite signal does not
diminish with the increase of the planet-moon separation beyond the Einstein
radius of the planet unlike the planetary signal which vanishes when the planet
is located well beyond the Einstein radius of the star. We also find that the
satellite signal tends to have the same sign as that of the planetary signal.
These tendencies are caused by the lensing effect of the star on the moon in
addition to the effect of the planet. We determine the range of satellite
separations where the microlensing technique is optimized for the detections of
moons. By setting an upper limit as the angle-average of the projected Hill
radius and a lower limit as the half of the Einstein radius of the planet, we
find that the microlensing method would be sensitive to moons with projected
separations from the planet of $0.05 {\rm AU} \lesssim d_{\rm p} \lesssim 0.24
{\rm AU}$ for a Jupiter-mass planet, $0.03 {\rm AU}\lesssim d_{\rm p} \lesssim
0.17 {\rm AU}$ for a Saturn-mass planet, and $0.01 {\rm AU} \lesssim d_{\rm p}
\lesssim 0.08 {\rm AU}$ for a Uranus-mass planet. We compare the
characteristics of the moons to be detected by the microlensing and transit
techniques
