Provided is a single-stranded oligonucleotide capable of controlling a gene of interest at high efficiency and being produced easily. A single-stranded oligonucleotide represented by the formula X-L-Y in which X and Y hybridize with a first nucleotide sequence portion and a second nucleotide sequence portion. X comprises 7-100 nucleotides, includes at least one modified nucleotide, can hybridize with a second oligonucleotide, and has a first nucleotide sequence including at least four consecutive nucleotides recognized by RNase H. Y comprises 4-100 nucleotides, can hybridize with the first oligonucleotide, and has a second nucleotide sequence including at least one ribonucleotide. Nucleotide sequence X and/or Y has an antisense sequence that can hybridize with an RNA of interest. L is a group derived from a third oligonucleotide that is degraded under physiological conditions.
