  The N\'eel and the singlet RVB orders of the {\it t-J} model in a 2D square
lattice are studied in the slave-boson mean-field approximation. It is shown
that the N\'eel order parameter takes the maximum value at the finite
temperature and disappear at the lower temperature for a certain range of
doping. It is also shown that the N\'eel and the singlet RVB orders coexist at
low temperature. This suggests the possibility of the coexistence of the N\'eel
and the superconducting orders.
