[Problem] A compound which is useful as an anti-obesity agent is provided. [Means for Solution] The present inventors have investigated a compound having a DGAT1 inhibitory action, which is promising as an active ingredient of a pharmaceutical composition for treating obesity, type II diabetes mellitus, fatty liver, and diseases associated with these diseases, and as a result, they have found that the diacylethylenediamine compound of the present invention has an excellent DGAT1 inhibitory action, thereby completing the present invention. That is, the diacylethylenediamine compound of the present invention has a DGAT1 inhibitory action, and can be therefore used as an agent for preventing and/or treating obesity, type II diabetes mellitus, fatty liver, and diseases associated with these diseases.
