This method for promoting plant growth treats plants with at least one compound selected from the group consisting of the compound indicated in formula (1) and an agriculturally acceptable salt thereof. However, methods for promoting plant growth by treating plants with the compounds corresponding to each of (1) to (5) below or agriculturally acceptable salts thereof are excluded. (1) 4-(trifluoromethyl)benzo[b]thiophene-2-carboxylate. (2) 5-(trifluoromethyl)benzo[b]thiophene-2-carboxylate. (3) 6-(trifluoromethyl)benzo[b]thiophene-2-carboxylate. (4) 7-(trifluoromethyl)benzo[b]thiophene-2-carboxylate. (5) Benzo[b]thiophene-2-carboxylate.
