  The ATLAS potential for the study of the top quark properties and physics
beyond the Standard Model in the top quark sector, is described. The
measurements of the top quark charge, the spin and spin correlations, the
Standard Model decay (t-> bW), rare top quark decays associated to flavour
changing neutral currents (t-> qX with X = gluon, Z, photon) and ttbar
resonances are discussed. The sensitivity of the ATLAS experiment is estimated
for an expected luminosity of 1fb-1 at the LHC. The full simulation of the
ATLAS detector is used. For the Standard Model measurements the expected
precision is presented. For the tests of physics beyond the Standard Model, the
5 sigma discovery potential (in the presence of a signal) and the 95%
Confidence Level (CL) limit (in the absence of a signal) are given.
