The anti sense chain, mRNA of the target gene continues arrangement of 17 bases which includes the arrangement of the complimentary base, it is the polynucleotide of length of 17 - 30 bases, the sense chain, 5 from terminal side of the said anti sense chain 3 facing toward terminal side, 1 - arrangement of the 17th base includes the arrangement of the complimentary base, being the polynucleotide of length of 17 - 30 bases, it connects to the base of position of specification of the said anti sense chain and the said sense chain the sugar which, in ratio of specification the respective deoxyribose or 2 hydroxyl group of rankIt is the ribose which is substituted with the decoration basis, being the composition which contains the liposome which encloses two these chain nuclear acid molecules, the said liposome, is the liposome which possesses the lipid double membrane which designates the lipid derivative, the fatty acid derivative or the aliphatic hydrocarbon derivative of the water soluble substance as the constitution component, the composition and the like is offered.アンチセンス鎖が、標的遺伝子のmRNAの連続する17塩基の配列と相補的な塩基の配列を含む、17~30塩基の長さのポリヌクレオチドであり、センス鎖が、該アンチセンス鎖の5’末端側から3’末端側に向って1~17番目の塩基の配列と相補的な塩基の配列を含む、17~30塩基の長さのポリヌクレオチドであって、該アンチセンス鎖および該センス鎖の特定の位置の塩基に結合する糖が、特定の割合でそれぞれデオキシリボースまたは2’位の水酸基が修飾基で置換されたリボースである、二本鎖核酸分子を封入したリポソームを含有する組成物であって、該リポソームが、水溶性物質の脂質誘導体、脂肪酸誘導体または脂肪族炭化水素誘導体を構成成分とする脂質二重膜を有するリポソームである、組成物等を提供する。
