  We investigate the Kondo effect in two-dimensional disordered electron
systems using a finite-temperature quantum Monte Carlo method. Depending on the
position of a magnetic impurity, the local moment is screened or unscreened by
the spin of the conduction electron. On the basis of the results, we show that
the distribution of the Kondo temperature becomes wide and the weight at
$T_K=0$ becomes large as randomness increases. The average susceptibility shows
a weak power-law or logarithmic divergence at low temperature, indicating a
non-Fermi-liquid behavior.
