The present invention provides compounds being useful as an agent for anti-cancer, an inducer for BET protein decomposition and an inhibitor for BET protein, wherein the above compounds have excellent cell damage action to cancer cells, excellent inducing action to BET protein decomposition in cancer cells, and excellent binding inhibition to BET protein and acetylated histone. The compounds provided in the present invention are represented by the following formula (I) or pharmaceutical acceptable salts thereof.(In formula, each symbol is same as it defined in the specification.)本發明提供對於癌細胞之細胞傷害作用、誘導癌細胞中BET蛋白質分解之作用及阻礙BET蛋白質與乙醯化組織蛋白結合之作用優越,有用於作為抗癌劑、BET蛋白質分解誘導劑及BET蛋白質阻礙劑之化合物。下述一般式(I)表示之化合物或其藥理學容許之鹽。{式中,各符號如說明書中之定義。}