A process for producing a nucleoside derivative (1) by reacting a substituted 2,3-dihydrofuran derivative (2) with an organohalogen compound (3) containing a group 16 element of the periodic table to give a substituted 2- halotetrahydrofuran derivative (4), condensing the derivative (4) with a nucleic acid base to give a substituted nucleoside derivative (5), and reducing the derivative (5), wherein R1 represents hydrogen, alkyl or R6-O-CH2-; R2 to R4 represent each hydrogen or a group containing a group 14-17 element of the periodic table; R5 represents optionally substituted alkyl or phenyl; A represents a group 16 element of the periodic table; B represents a nucleic acid base; and X represents halogen.