The purpose of the present invention is to obtain novel therapeutic drugs for malignant tumors, methods for producing a stem cell, or DNA damage-ameliorating agents, etc., wherein a HAT1 and KAT8 inhibitor is used； a kit containing a HAT1 inhibitor and a KAT8 inhibitor may be used； a composition comprising a HAT1 inhibitor, wherein the HAT1 inhibitor is used in combination with a KAT8 inhibitor, may be used； or a composition comprising a KAT8 inhibitor, wherein the KAT8 inhibitor is used in combination with a HAT1 inhibitor, may be used.
