Remarkable advances have been made in cancer immunotherapy. Recent treatment strategies, especially chimeric antigen receptor-T (CAR-T) cell therapy and immune checkpoint inhibitors, reportedly achieve higher objective responses and better survival rates than previous immunotherapies for patients with treatment-resistant malignancies, creating a paradigm shift in cancer treatment. Several clinical trials of cancer immunotherapy for patients with various malignancies are ongoing. However, those with certain malignancies, such as low-immunogenic cancers, cannot be successfully treated with T-cell immunotherapy, and subsets of immunotherapy-treated patients relapse, meaning that more effective immunotherapeutic strategies are needed for such patients. Furthermore, the safety, convenience, and cost of cancer immunotherapy need to be improved in the near future. Herein, we discuss recent advances and future challenges in cancer immunotherapy, i.e., the identification of neoantigens for the development of individualized immunotherapies, the development of new CAR-T cell therapies, including so-called armored CAR-T cells that can induce greater clinical effects and thereby achieve longer survival, the development of off-the-shelf treatment regimens using non-self cells or cell lines, and effective cancer immunotherapy combinations.