  We report our analyses of the multi-epoch (2015-2017) ALMA archival data of
the Class II binary system XZ Tau at Bands 3, 4 and 6. The millimeter dust
continuum images show compact, unresolved (r <~ 15 au) circumstellar disks
(CSDs) around the individual binary stars; XZ Tau A and B, with a projected
separation of ~ 39 au. The 12CO (2-1) emission associated with those CSDs
traces the Keplerian rotations, whose rotational axes are misaligned with each
other (P.A. ~ -5 deg for XZ Tau A and ~ 130 deg for XZ Tau B). The similar
systemic velocities of the two CSDs (VLSR ~ 6.0 km s-1) suggest that the
orbital plane of the binary stars is close to the plane of the sky. From the
multi-epoch ALMA data, we have also identified the relative orbital motion of
the binary. Along with the previous NIR data, we found that the elliptical
orbit (e = 0.742+0.025-0.034, a = 0''.172+0''.002-0''.003, and {\omega} =
-54.2+2.0-4.7 deg) is preferable to the circular orbit. Our results suggest
that the two CSDs and the orbital plane of the XZ Tau system are all misaligned
with each other, and possible mechanisms to produce such a configuration are
discussed. Our analyses of the multi-epoch ALMA archival data demonstrate the
feasibility of time-domain science with ALMA.

Solar and Stellar Astrophysics;Earth and Planetary Astrophysics;Astrophysics of Galaxies