A desulfurization adsorbent for a fuel cell has a structure according to Formula 1 below, and a desulfurizing method uses the desulfurization adsorbent. The desulfurization adsorbent displays remarkably excellent adsorption performance for adsorbing sulfur compounds as well as excellent regeneration performance, compared with conventional desulfurization adsorbents. Thus, the desulfurization adsorbent does not need to be replaced even after prolonged use, thus stabilizing the operation of a fuel cell system and reducing costs.(M1)a-(Si)x—(Ti)y-(M2)z-O [Formula 1]wherein M1 is at least one selected from alkali metals, alkaline earth metals, hydrogen, ammonium, rare earths, and transition metals; 4≦x / y≦500, 0≦z / y≦3, 0≦a / (y+z)≦1; and M2 is aluminum (Al), boron (B) or a trivalent metal. The desulfurization adsorbent is produced by subjecting a mixture of a silicon source, a titanium source, and optionally, aluminum, boron or a trivalent metal in an alkali solution to a hydrothermal treatment to obtain a crystalline porous molecular sieve.