Developer for developing electrostatic latent image and image forming method

An image forming method, which comprises forming an electrostatic latent image on a photosensitive drum;

• developing said latent image with a developer to form toner images, said developer comprising negatively chargeable toner particles and, hydrophobic, negatively chargeable silica fine powder,
• said silica fine powder being obtained by treating silica fine powder with a silane coupling agent represented by the following formula:
• R.sub.m SiY.sub.n or Y.sub.3 --Si--NH--Si--Y.sub.3
• wherein R represents alkoxy group or chlorine atom, Y represents alkyl group, m represents positive integer of 1 to 3 and n represents positive integer of 3 to 1, with proviso that m+n is 4,
• and treating further said treated silica fine powder with a silicone oil having the structure:
• ##STR15## wherein R represents alkyl group having 1 to 3 carbon atoms, R' represents alkyl group different form R having 1 to 10 carbon atoms, halogen-modified alkyl group having 1 to 10 carbon atoms, phenyl-modified alkyl group or phenyl group, R" represents alkyl group having 1 to 3 carbon atoms or alkoxy group having 1 to 3 carbon atoms (with proviso that R" represents a group which may be either the same as or different from R), and x and y each represent positive integer;
• electrostatically transferring the toner images formed to a transfer material;
• and cleaning the photosensitive drum after electrostatic transfer with a blade cleaning means.