The present invention provide a mold for forming a developer blade and a developer blade manufactured with such a mold which are able to give images of good quality even in the low-temperature low-humidity condition and to improve a mold releasability. A mold 10 for forming a developer blade has a plate accommodation space 14 in which the metal plate is accommodated and a belt-like cavity 15 for forming the elastic member adjacent to the plate accommodation space. At least a part 20a of a cavity surface 20 defining the cavity 15 in the cross section taken along the cavity width direction is finished to have a surface roughness Ry of not more than 10 μm.