PROBLEM TO BE SOLVED: To obtain an effective and safe plant activator for promoting growth of a plant, especially a plant belonging to plant C3, increasing a carbohydrate content of root, stem and leaf and fruit, having an extremely low load to the environment. SOLUTION: This plant activator is obtained by macerating a wood of a plant of the family Pinaceae or its small piece with a lower alicyclic alcohol or a hydrous lower aliphatic alcohol to give an extracted solution or an extracted essence containing the active ingredient of the plant and formulating the extracted solution or the extracted essence with trehalose.
