The invention relates to sense oligonucleotide having a sequence complementary to a single-stranded RNA (antisense transcript) having a sequence complementary to mRNA of iNOS gene in order to control expression of iNOS (inducible nitric oxide synthase). The sense oligonucleotide of the present invention can control expression of iNOS and is useful for biological defense and treatment and prevention of diseases related to excessive production of NO, such as cancerogenesis, inflammatory disease, endotoxin shock by bacterial infection and the like.