The present invention provides: a composition for silencing a CKAP5 gene, the composition containing, as a drug, double-stranded nucleic acid that has a sequence of bases complementary to a sequence of at least 19 successive bases of mRNA of a CKAP5 gene having an antisense strand of any of SEQ ID NOS: 1-6, and lipid particles that contain a cationic lipid represented by formula (I) (in the formula, R