A composition comprising a substance represented by general formula (I), a pharmaceutically acceptable carrier and a dissolution aid is useful for the improvement in the solubility, oral absorbability and/or absorbability in blood of the poorly-water-soluble or water-insoluble tetracyclic compound that is useful as a prophylactic and/or therapeutic agent for cancer, depression and cognitive dysfunction and has an ALK inhibitory activity. [In the formula, the symbols are as defined in the description.]
