The desorption characteristics of NaY zeolite, of which Si/Al ratio is 2.36, was measured at 25${circ}$C and 150${circ}$C so as to be used practically as a adsorbent for separation of sulfur oxides from flue gas, for which adsorption and desorption cycles at 25${circ}$C were repeated four times and that at 150${circ}$C was done one time. As a result it took 30.8 at 150${circ}$C and 164.1 minutes in average at 25${circ}$C to reach equilibrium condition. It means that regeneration of the NaY zeolite can be done below 150${circ}$C so that zeolite can be used for flue gas desulfurization.