Acylguanidine derivative or salt thereof

2B 7 2B 7 2B 7 [Problem] To provide a compound which can be used in the prevention and/or treatment of diseases in which 5-HTreceptor and 5-HTreceptor are concerned, particularly in the treatment of irritable bowel syndrome (IBS) and/or prevention of migraine.[Means for Resolution] It was found that an acylguanidine derivative having a tricyclic structure or a pharmaceutically acceptable salt thereof has a strong antagonism to 5-HTreceptor and 5-HTreceptor. In addition, the compound of the present invention having antagonism to both of the receptors showed superior pharmacological action in comparison with the case of the single use of an antagonist selective for either one of the receptors. Based on the above, the compound of the present invention is useful in preventing and/or treating diseases in which 5-HTreceptor and 5-HTreceptor are concerned, particularly in treating irritable bowel syndrome (IBS) and/or preventing migraine.