Patent ID: 7751730

Claim:
A developing device comprising: a developer conveying device configured to convey a developer containing a toner and a carrier; and a developer holding unit configured to convey the developer conveyed by the developer conveying device to an area facing a latent-image holding unit in accordance with its own surface movement by holding the developer on its own endlessly-moving surface, and develop a latent image held by the latent-image holding unit, wherein the developer conveying device includes: a developer conveying unit configured to convey a developer containing a toner and a carrier in a rotation axis direction while agitating the developer with rotation of an agitation conveying member, and a toner-concentration detecting unit configured to detect a toner concentration of the developer by having contact with the developer conveyed inside the developer conveying unit or facing the developer via a wall of the developer conveying unit; and an average of maximum amounts of a pressing force on the developer, which is conveyed inside the developer conveying unit by the agitation conveying member, by each one rotation of the agitation conveying member with respect to the toner-concentration detecting unit or an average of maximum amounts of a pressing force on the developer by each one rotation of the agitation conveying member with respect to a portion of the wall facing the toner-concentration detecting unit is set within a range of 9.8×15 [N/m 2 ] to 9.8×100 [N/m 2 ].