Provided is a somatostatin receptor subtype-2 agonist. A compound represented by general formula (I) [wherein each symbol has the same meaning as defined in the description], a salt thereof, an N-oxide thereof or a solvate thereof, or prodrugs of the same, which are low-molecular compounds having potent agonistic activity to somatostatin receptor subtype-2 and, therefore, can be administered in a simpler manner and have high safety and low toxicity, are useful in preventing and/or treating somatostatin-related diseases such as acromegaly and gastrointestinal obstruction.