The invention provides a single-stranded nucleic acid molecule for inhibiting the expression of a prorenin gene or a prorenin receptor gene, wherein the nucleic acid molecule is characterized in that the nucleic acid molecule comprises only a region (X), a linker region (Lx), and a region (Xc)； the linker region (Lx) has a non-nucleotide structure including a pyrrolidine skeleton and/or a piperidine skeleton； and the region (X) and/or the region (Xc) includes a base sequence of at least 18 consecutive bases among any of the prorenin gene expression-inhibiting sequences represented by SEQ ID NOS: 1 to 5 and prorenin receptor gene expression-inhibiting sequences represented by SEQ ID NOS: 6 to 11.
