The invention provides a cut-out method capable of suppressing production of a byproduct, wherein the object RNA oligonucleotide is not cleaved from a universal linker, which is produced in cutting out the object RNA oligonucleotide from the universal support, and capable of increasing the yield of the object RNA oligonucleotide. The RNA oligonucleotide cut-out method includes a step of bringing a universal support supporting an RNA oligonucleotide in contact with an aqueous solution containing alkylamine and a monovalent inorganic salt.