PROBLEM TO BE SOLVED: To provide an excellent dendron negative regulatory agent and to provide a screening method of a dendron regulatory agent using it.SOLUTION: The invention relates to a dendron negative regulatory inhibitor containing an extract of Crassulaceae Rhodiola plants as an active ingredient and the dendron negative regulation may be dendron formation suppression, dendron regression, or dendron activation suppression. The plant may be Rhodiola Sacra and/or Rhodiola crenulata. And it relates to a screening method of the dendron regulatory agent using the extract of Crassulaceae Rhodiola plants.