PURPOSE: To obtain a static charge developing negatively-chargeable toner having superior characteristics in frictional electricity and free from an image quality deterioration due to repeated development by adding a specified diazo compound to a resin.

CONSTITUTION: To a binding resin such as styrene type resin or polyester resin is added about 0.1W10wt% of a diazo compound represented by general formula I (where R1 is lower alkyl; each of R2 and R3 is H or hydroxyl; R4 or lower alkyl; and R5 is H, acyl or amino having a terminal acyl group), e.g. the compound of formula II or III. Thus, a toner is obtd.