A developing device includes (a) a developing member; (b) a developer container; (c) a partition member that partitions an interior of the developer container into a primary chamber and a secondary chamber; and (d) a developer-conveying unit that is disposed in the primary chamber, the developing device defining a collected-toner-receiving port through which a collected toner that is collected from a toner image carrier is received into the developer container; and a migration opening through which a developer held in the primary chamber is migratable to the secondary chamber, the developing device further including (e) a capturing unit that is disposed at the migration opening and captures a foreign material which migrates through the migration opening together with the developer; and (f) a foreign-material-removing unit that is disposed at the developer-conveying unit and moves the foreign material out of the developer container in accordance with the rotation of the developer-conveying.