<p>The purpose of the present invention is to improve sealing characteristics of a seal member in a developing device equipped with a developing roller having a fiber layer. The developing device comprises: a housing for storing a developer; a developing roller (20) having a fiber layer formed on the outer periphery of the roller body (22); a plate-shaped regulating blade (30) which is brought into contact with the fiber layer to regulate the amount of the developer carried by the fiber layer; and seal members (40) arranged between the housing and the ends of the roller body (22) in the axial line direction. The regulating blade (30) includes a main body (31) extending along the developing roller (20) with the upper end (31A) fixed to the housing; and a bent portion (32) extending from the free end (lower end (31B)) of the main body (31) toward the developing roller (20) with the tip end (32A) brought into contact with the fiber layer. The bent portion (32) is formed axially inward of the end surfaces (31E) of the main body (31) in the axial line direction. The seal member (40) is brought into contact with both the end surfaces (32E) of the bent portion (32) in the axial line direction, and the portions (outside portions (31F)) of the main body (31) axially outward of the bent portion (32).</p>
