The invention provides a process for producing the crystals of difructose dianhydride III (DFA III), namely a indigestible disaccharide where two fructose molecules are bonded to each other at positions 1,2' and 2,3'(di-D-fructofuranose-1,2':2,3'-dianhydride), where solutions containing DFA III are adjusted to and/or maintained at pH 5 or more, preferably pH 5 to 8, and more preferably 6 to 8. In accordance with th invention, DFA III can be produced industrially without lowering the crystal yield even when the crystallization thereof is done in a recycling system; additionally by adjusting the total fructose content in mother solutions for (crude) crystallization to 5% or less per a solid content basis and adjusting the fructose content to 1% or less, DFA III can more effectively be produced.