PURPOSE: To stably obtain an image which does not have fogging and ghost, whose density is high and which has high quality, with a simple constitution.

CONSTITUTION: Toner 2 is carried to the rear side of an elastic roller 7 by the rotation of a toner feeding member 12, and a means 8 for detecting the left amount of developer is pushed upward. The elastic roller 7 supplies the toner 2 to a sliding part between the elastic roller 7 and a developing sleeve 3. Next, at the sliding part between the developing sleeve 3 and the elastic roller 7, the toner on the elastic roller 7 is slid by the developing sleeve 3, so that it is tribo-electrified, and also supplied to the developing sleeve 3. The detecting means 8 for detecting the left amount of the developer detects whether the toner always exists on the upward position of the elastic roller 7 or not.