It is intended to develop a technique that can reproduce a microenvironment of cancer tissue and to construct a novel drug discovery screening system of high precision. It is also intended to provide a method for reconstituting human cancer tissue using primary human cancer cells that retain the properties of human tumor. The present invention provides a reconstituted cancer organoid reproducing a cancer microenvironment. The present invention also provides a method for preparing a cancer organoid from cancer tissue, a xenograft prepared from the cancer organoid, a method for preparing the xenograft, a method for evaluating treatment resistance of cancer, a method for evaluating invasion or metastasis of cancer, a method for evaluating recurrence of cancer, and a method for conducting prognostic prediction of cancer.
