A modified nucleotide n-mer (where n is an integer of 2 or more) is used which comprises a nucleoside unit with a substituent group introduced into the base, wherein the substituent group is bound to the base via a triple bond. Novel nucleotide oligomers, nucleotide polymers, and nucleosides which can be used as raw materials or intermediates in the synthesis of this nucleotide oligomer and nucleotide polymer, as well as novel techniques for structural determination and manufacture of a functional substance having high affinity for a target, are provided.