A two-component developing device using a developer containing toner and magnetic carrier particles. The developing device comprises a housing, a developing roller, a magnetic field generator mounted inside the developing roller, and a developer restricting member, and further comprises a developer guide member providing a developer guide path for guiding the developer to the developer amount restricting clearance, providing a developer circulation path for circulating the developer to an upstream end of the guide member, and providing a communication path for bringing the developer guide path into communication with the developer circulation path, an upstream end of the guide member being positioned above the position of a peak of magnetic flux density of the magnetic pole of the magnetic field generator which is closest to a low-magnetic force area downstream of the low-magnetic force area or positioned upstream of such a position and downstream of the low-magnetic force area. An image forming device in which such a two-component developing device is employed as at least one developing device.