The present invention discloses a 5'-amino-2'-fluoro-2',5'-dideoxynucleoside derivative represented by the following formula [1]: (wherein R.sub.1 represents a nucleic acid base which may have a protecting group; R.sub.2 represents a hydrogen atom or a protecting group of an amino group; R.sub.3 represents a hydrogen atom or a protecting group of a hydroxyl group); a dideoxynucleoside-insoluble carrier bound substance prepared by binding said dideoxynucleoside derivative to an insoluble carrier, and an oligonucleotide analogue into which said dideoxynucleoside derivative is introduced. The oligonucleotide analogue being introduced with a dideoxynucleoside derivative of the present invention has excellent thermal stability and also high binding affinity when duplex is formed. Also, it is anticipated that it has high resistance to nucleases. Further, the dideoxynucleoside derivative of the present invention can be used as an amidite reagent to be used for nucleic acid synthesis, and also as a starting material for solid phase synthesis of nucleic acid by binding the amidite reagent to a solid phase.