A method for producing 2'-deoxy-2'-fluoro-.beta.-D-arabinonucleoside represented by formula (II): ##STR00001## (wherein B represents a base), in particular, 2'-deoxy-2'-fluoro-.beta.-D-arabinopurinenucleoside, which method comprises causing a nucleoside phosphorylase to act on .alpha.-1-phosphorylated-2-deoxy-2-fluoroarabinoside represented by formula (I): ##STR00002## or a mixture of .alpha.- and .beta.-isomers of 1-phosphorylated-2-deoxy-2-fluoroarabinoside represented by formula (V'): ##STR00003## and on a base. The compound can be produced at high yield and in a convenient and highly stereoselective manner.