To realize high-quality prints, by setting a control unit having an aperture passing tone particles and finely adjusting a gap between a developing sleeve and the aperture by a slidable alignment edge part.

A particle feed unit 2 is constituted of a particle container 21, a particle feeder 25, a rotary feed brush 24, an adjusting blade 26 and a rotary developing sleeve 23 which as a surface where thin layers of uniformly charged toner particles 20 are piled. A back electrode 1 is set via a distance to the unit 2. the toner particles 20 are charged through contact with the feed brush 24 and charge exchange to a surface material of the sleeve 23. A plurality of apertures 31 as a part of a control unit 3 are formed between alignment edge parts 51 slidable to a tension application edge part 50, so that the particles pass through the control unit 3 from a surface 22 of the sleeve to the back electrode 1.