Abstract: The present invention relates to a production method of (R)-reticuline including: a step for obtaining a recombinant host cell by inserting, into a host cell, a gene 1 which is composed of a nucleotide sequence having at least 70% homology to a nucleotide sequence of SEQ ID NO: 2 and which is DNA encoding a protein having an enzymatic activity of CYP80Y2, and a gene 2 which is composed of a nucleotide sequence having at least 70% homology to a nucleotide sequence of SEQ ID NO: 3 and which is DNA encoding a protein having an enzymatic activity of oxidoreductase; a step for expressing, in the recombinant host cell, the protein having the enzymatic activity of CYP80Y2 and the protein having the enzymatic activity of oxidoreductase; and a step for producing (R)-reticuline from (S)-reticuline by using the recombinant host cell.