[Problem] To provide a compound which is useful as an active ingredient of a pharmaceutical composition, especially of a pharmaceutical composition for the prophylaxis and/or treatment of VAP-1 associated diseases.[Solution] As a result of intensive studies on a compound having VAP-1 inhibitory activity, the inventors have achieved the present invention by discovering that a compound of the present invention or a salt thereof has excellent VAP-1 inhibitory activity and is thus useful for the prophylaxis and/or treatment of VAP-1 associated diseases, especially for the prophylaxis and/or treatment of diabetic nephropathy or diabetic macular edema. The present invention also relates to a pharmaceutical composition, particularly a pharmaceutical composition for the prophylaxis and/or treatment of VAP-1 associated diseases, said pharmaceutical composition containing a compound of the present invention or a salt thereof and an excipient.
