Provided is an RNA interference-inducing nucleic acid comprising at least one nucleic acid strand, the at least one nucleic acid strand comprising a modification substituted to a spacer, which is unable to form a base pair, in the 5′ end or the 3′ end region. The RNA interference-inducing nucleic acid is a modified form of nucleotide provided to prevent off-target effects, offering a method to selectively repress target gene expression. The RNA interference-inducing nucleic acid provides modified forms with target selectivity and specificity as a method to block the off-target effects while silencing the target gene expression, whereas the usage of conventional RNA interference-inducing nucleic acids cause inaccuracy and adverse effects through off-targets, thereby the RNA interference-inducing nucleic acid was offered to solve the problem, wherein it will be widely used as a method for repressing gene expression in research and for gene therapy without concerning the off-target effects.