The present application discloses a therapeutic agent for breast cancer, which comprises 5-((2-(4-(1-(2-hydroxyethyl)piperidin-4- yl)benzamide)pyridin-4-yl)oxy)-6-(2-methoxyethoxy)-N- methyl-1H-indole-1-carboxamide or a pharmacologically acceptable salt thereof.La presente solicitud describe un agente terapéutico para el cáncer de mama que comprende 5-((2-(4-(1-(2-hidroxietil)piperidin- 4-il)benzamido)piridin-4-il)oxi)-6-(2-metoxietoxi)-N-metil-1H-ind ol-1-carboxamida o una sal farmacológicamente aceptable de esta.