PURPOSE: To efficiently mass-produce a berberine type alkaloid, by cultivating a plant cell and/or tissue thereof using a culture medium having an ammonium ion concentration of ≥50% based on the total inorganic nitrogen concentration.

CONSTITUTION: A culture medium which is conventionally known and used for tissue culture of a plant in an ammonium ion concentration ratio of ≥50%, preferably about ≥70% based on the total nitrogen concentration is employed to cultivate a cell and/or tissue of a plant, e.g., ranunculaceous plant of the genus, such as Coptis or Thalictrum.