PROBLEM TO BE SOLVED: To provide a silencing suppressor.SOLUTION: There is provided a system capable of screening a DNA sequence, which suppresses silencing, from a genomic library by selecting a system in which silencing happens in high frequency, and using activity which suppresses the silencing as an index. In addition, the obtained DNA sequence is ascertained to have activity for suppressing silencing differently caused in a plurality of plants. (The element having silencing suppression activity originated from genome may be called as the anti-silencing region=ASR). By these means, identification and isolation of the DNA sequence expressing stable and strong silencing suppression effects in plant species can be performed.
