In a toner collecting device of the cyclone separator type that collects toner separated from air, exhaust of the air including unseparated toner to outside the cyclone separator, which is caused by an unstable sucking operation of a cyclone blower, can be prevented. The toner collecting device includes a blocking unit that blocks airflow generated by the suction of the cyclone blower while the sucking operation of the cyclone blower is not in a steady state.