The present invention provides a process cartridge that is freely attachable to and detachable from a main body of an image forming apparatus and that includes a latent image bearing body and a developing device having a developer storage space for storing a developer, the image forming apparatus and an image forming method. The invention also provides another image forming method using a one-component magnetic toner that is employable in a wide region of from a low process speed to a high process speed while achieving a high fixing ability.