To provide a developing device capable of supplying toner into the developing device, without the supplied toner to overflow, using a simple constitution and surely mixing and stirring the supplied toner and developer, and to provide an image forming apparatus that uses the developing device.

The developing device 12 includes: a housing 234 storing developer; a developing roller 231 for supplying toner to a photoreceptor drum 21 on which an electrostatic latent image is formed; and a first toner conveyance shaft 232 and second toner conveyance shaft 233, used to stir and convey developer in the housing 234. The developing device 23 renders an electrostatic latent image, formed on the photoreceptor drum 21, visible with toner, and the housing 234 has a toner inlet 234a for guiding toner to the inside, from the outside. A magnet 250 is disposed adjacent to the toner inlet port 234a.