PURPOSE: To form an image excellent in environmental stability and the same quality as that of the initial image even after continuous copying by incorporating each specified compd. as a charge controlling agent and an assistant agent.

CONSTITUTION: This toner essentially consists of a binder resin, coloring agent and charge controlling agent. The charge controlling agent is a compd. expressed by formula I. In formula I, n is an integer 1 to 3. The assistant agent for the charge controlling agent is at least one compd. selected from the following compds. (a) to (c). (a) is a copolymer containing 1-50wt.% repeating unit expressed by formula II and 50-99wt.% compd. selected from styrene or its substd. compd., acrylic acid, acrylate, methacrylic acids. The copolymer has 2000-20000 weight average mol.wt. In formula II, R1 is hydrogen or a methyl group, R2 is an alkylene group, R3-R5 are methyl groups, ethyl groups, or propyl groups, R6 is a methyl group, ethyl group, or propyl group, X is -COO- or -CONH-, (b) is a quaternary ammonium salt compd., and (c) is a nigrosine compd.