[Problem] To provide a compound which is useful as a novel and excellent prophylactic and/or therapeutic agent for rejection in various types of organ transplantation allergic diseases autoimmune diseases and blood tumors and which acts in a manner relying on a PI3Kd selective inhibitory activity and/or an IL 2 production inhibiting activity and/or a B cell proliferation inhibiting activity (including an activation inhibiting activity). [Solution] Examination was made on compounds each having a PI3Kd selective inhibitory activity and/or an IL 2 production inhibiting activity and/or a B cell proliferation inhibiting activity (including an activation inhibiting activity) and it has been confirmed that a hetero ring compound having a chemical structure represented by formula (I) has a PI3Kd selective inhibitory activity and/or an IL 2 production inhibiting activity and/or a B cell proliferation inhibiting activity (including an activation inhibiting activity).
