Abstract: Disclosed is a magnetic one-component toner for development of an electrostatic latent image used in a magnetic one-component jumping development system in which a photoconductor is an a-Si photoconductor having a thickness of 30 ?m or less and Rz of a developer carrier is from 2.0 to 6.0 ?m. A cleaning means for removing the toner from the surface of the photoconductor is a cleaning blade. Titanium oxide, as an external additive, is added to the toner. The titanium oxide has a liberation rate within a range from 10 to 22% and contains a low resistance titanium oxide having a volume resistivity within a range from 100 to 107?·cm and a high resistance titanium oxide having a volume resistivity within a range from 108 to 1013?·cm, a mass ratio of the low resistance titanium oxide to the high resistance titanium oxide within a range from 1.3:1 to 4:1.