PURPOSE: To prevent a fact that recording of a longitudinal line becomes pale in comparison with a lateral line, by providing plural magnets which diagonally cross a line being in parallel with a bus of a rotary sleeve of a developing roll, and are placed like a stripe, by fixing them to the inside circumferential part of the rotary sleeve.

CONSTITUTION: Plural magnets 3' which diagonally cross a line being in parallel with a bus of a rotary sleeve 2, and are placed like a stripe are provided by fixing them to the inside circumferential part of a part where the rotary sleeve 2 is close to a rotary drum 1. In this regard, the magnet 3' crosses its lengthwise direction and is provided with polarity in the circumferential direction of the sleeve 2. As for a developing roll having such a structure, the magnetic brush is formed to a pattern as shown in the figure, on the outside circumference of the sleeve 2. The magnetic brush of this pattern has depth in the outside circumferential direction of the rotary sleeve 2, therefore, a toner is replenished enough to the longitudinal line, too. Therefore, it is prevented that recording of the longitudinal line becomes pale in comparison with the lateral line, and the picture quality can be improved.