  We developed a new method for full kinematical reconstruction of the ttbar
system near its threshold at future linear e+e- colliders. In the core of the
method lies likelihood fitting which is designed to improve measurement
accuracies of the kinematical variables that specify the final states resulting
from ttbar decays. The improvement is demonstrated by applying this method to a
Monte-Carlo ttbar sample generated with various experimental effects including
beamstrahlung, finite acceptance and resolution of the detector system, etc. In
most cases the fit brings a broad non-Gaussian distribution of a given
kinematical variable to a nearly Gaussian shape, thereby justifying
phenomenological analyses based on simple Gaussian smearing of parton-level
momenta. The standard deviations of the resultant distributions of various
kinematical variables are given in order to facilitate such phenomenological
analyses. A possible application of the kinematical fitting method and its
expected impact are also discussed.
