The present invention provides a novel cancer treatment method which exhibits remarkably excellent antitumor effect and has few side effects. An antitumor agent characterized by the simultaneous release of a DNA functional group and an immunomodulator.현저하게 우수한 항종양 효과를 나타내고, 부작용이 적은 신규한 암치료 방법의 제공. DNA 기능 장해제와 면역 조절제를 병용 투여하는 것을 특징으로 하는 항종양제.