The present invention relates to a transglutaminase inhibitor comprising epigallocatechin gallate (hereinafter, referred to as EGCG). More particularly, the present invention relates to a transglutaminase inhibitor comprising EGCG which effectively inhibits the activity of transglutaminase, the overexpression of which is responsible for the etiology of various diseases, and to novel uses thereof. According to the present invention, provided is a transglutaminase inhibitor and a method of inhibiting transglutaminase, featuring the use of EGCG as an active ingredient. Featuring the use of EGCG, the novel method of inhibiting transglutaminase according to the present invention is safely applied to patients who suffer from the diseases caused by the overexpression of transglutaminase, thereby obtaining an inhibitory effect against transglutaminase without casuing side-effects.
