This invention relates to a novel fluorene derivative having a characteristic structure in which guanidino group or the like functional group is linked to the fluorene structure via carbonyl group, or a salt thereof. The compound of the invention has an advantage in that it has high affinity for serotonin receptor subtypes, particularly for 5-HT 2B receptor and 5-HT 7 receptor, and shows excellent pharmacological effects in comparison with the conventional compounds which have only one of the antagonistic activities of 5-HT 2B receptor and 5-HT 7 receptor, this is useful as a prophylactic antimigraine agent having high safety and excellent effect.
