Nonmagnetic one component developer and developing method

A developing method comprising arranging a developing roller carrying a developer charged to the same polarity as the charged polarity of the charged surface of a photosensitive member in contact with the photosensitive member, exposing the photosensitive member, and then developing an exposed region on the photosensitive member with the developer, and at the same time removing a remaining developer adhered to a non-exposed region on the photosensitive member by suction on the side of the developing roller to conduct cleaning, wherein the developer is a non-magnetic one-component developer comprising a substantially spherical polymerized toner which contains at least a binder resin and a colorant and has the following features:

• (a) the volume average particle diameter being 5 to 10 μm;
• (b) the proportion of particles having a particle diameter of at most 5 μm being at most 25% by number;
• (c) the proportion of particles having a particle diameter of at least 16 μm being at most 2% by volume;
• (d) the standard deviation of the number particle diameter distribution being at most 1.8;
• and
• (e) the spheroidicity represented by a ratio (dl/ds) of a length (dl) to a breadth (ds) in a particle being 1.0 to 1.3.