Functional nucleic acid transfer expression system

[Summary] The present invention provides a novel ribozyme and its expression system. A ribozyme comprising a nucleotide sequence having the following nucleotide sequence (I) or (II). Nucleotide sequence (I): 5'-ACCGUUGGUUUCCGUAGUGUAGUGGUUAUCACGU UCGCCUAACACGCGAAAGGUCCCCGGUUCGAAACCGGGCACUACAAACAC AACACUGAUGAGGACCGAAAGGUCCGAAACGGGCACGUCGGAAACGGUUU UU-3 'nucleotide sequence (II): 5'-ACCGUUGGUUUCCGUAGUGUAGUGGUUAUCACG UUCGCCUAACACGCGAAAGGUCCCCGGUUCGAAACCGGGCACUACAAACC AACACACAACACUGAUGAGGACCGAAAGGUCCGAAACGGGCACGUCGGAA ACGGUUUUU-3 '