Patent ID: 8918035

Claim:
A developing apparatus comprising an electrostatic latent image bearing member on which an electrostatic latent image is formed, magnetic toner for developing the electrostatic latent image, a magnetic toner-carrying member arranged so as to oppose the electrostatic latent image bearing member for carrying and transporting the magnetic toner, and a toner regulating member contacting the magnetic toner-carrying member and regulating the magnetic toner carried on the magnetic toner-carrying member, wherein: the magnetic toner-carrying member has a work function value at the surface of 4.6 eV or more and 4.9 eV or less, a portion of the toner regulating member, which is contacting the magnetic toner, is made of a polyphenylene sulfide or a polyolefin, and the magnetic toner i) comprises magnetic toner particles, each of which contains a binder resin and magnetic powder, and silica fine powder, ii) has negative charging property, iii) has a ratio [W/B] of an amount W (mass % relative to the magnetic toner) of the silica fine powder to a theoretical specific surface area B (m 2 /g) of the magnetic toner determined from particle diameter distribution (number statistical value) satisfying the following formula (1): 2.5 ≦W/B≦ 10.0. (1)