[Object]A novel and excellent method for preventing or treating rejection in the transplantation of various organs, allergy diseases, autoimmune diseases, hematologic tumor, or the like, based on a PI3Kδ-selective inhibitory action and/or an IL-2 production inhibitory action, and/or a B cell proliferation inhibitory action (including an activation inhibitory action), is provided[Means for Solution]It was found that a 3-substituted triazine or 3-substituted pyrimidine derivative exhibits a PI3Kδ-selective inhibitory action, and/or an IL-2 production inhibitory action, and/or a B cell proliferation inhibitory action (including an activation inhibitory action), and can be an agent for preventing or treating rejection in the transplantation of various organs, allergy diseases (asthma, atopic dermatitis, etc.), autoimmune diseases (rheumatoid arthritis, psoriasis, ulcerative colitis, Crohn's disease, systemic lupus erythematosus, etc.), hematologic tumor (leukemia etc.), or the like, thereby completing the present invention.
