A development apparatus for developing latent electrostatic images to visible or transferable images of high quality for use in electrophotographic copying apparatus, electrostatic recording apparatus, facsimile apparatus or other recording apparatus, in which a development roller is in arc-contact with a latent-electrostatic-image-bearing flexible recording medium and is capable of supplying a sufficient amount of toner to the recording medium for development of the latent electrostatic images, without requiring any delicate adjustment of the gap between the development roller and the recording medium or of the gap between the development roller and a doctor blade for regulating the thickness of a toner layer on the development roller, and without increasing the rotary speed of the development roller to conventional speeds, and the doctor blade is also capable of performing charge injection to the toner with high efficiency, whereby images can be developed with high quality with a minimum deposition of toner on the background.