Image forming apparatus and image formation method

An image forming apparatus comprising:

• a magnetic toner;
• an image bearing member;
• and
• a development device that develops an electrostatic latent image formed on the image bearing member into a toner image with the magnetic toner, wherein
• the image bearing member is an amorphous silicon photosensitive drum,
• the magnetic toner includes toner particles,
• the toner particles each include a toner mother particle containing a binder resin and a magnetic powder and alumina particles attached to a surface of the toner mother particle,
• the alumina particles each include a core containing alumina and a conductive layer covering the core, the conductive layer containing antimony tin oxide,
• the alumina particles have a number average primary particle diameter of at least 0.15 μm and no greater than 0.50 μm,
• the alumina particles have a specific resistance of no greater than 250 Ω·cm, and
• the alumina particles have an X-ray intensity ratio of at least 0.25 and no greater than 0.35, the X-ray intensity ratio of the alumina particles being a ratio of an X-ray intensity of a peak derived from an antimony element contained in the alumina particles to an X-ray intensity of a peak derived from a tin element contained in the alumina particles, the X-ray intensity of the peak derived from the antimony element and the X-ray intensity of the peak derived from the tin element being measured by X-ray fluorescence analysis.