A compound represented by the general formula (I) or a salt thereof. LSD1 inhibitor which uses the said compound or its salt as an active ingredient. A pharmaceutical composition containing the compound or a salt thereof. An antitumor agent comprising the compound or a salt thereof as an active ingredient.一般式(I)で表される化合物又はその塩。当該化合物又はその塩を有効成分とするLSD1阻害剤。当該化合物又はその塩を含有する医薬組成物。当該化合物又はその塩を有効成分とする抗腫瘍剤。