Charge control agent and toner using same

The present invention provides a charge control agent containing, as an active substance(s), one or two or more thiazolidinedione derivatives represented by the following formula (1), where R1 represents a hydrogen atom, etc.; R2 represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent, etc.; R3 to R7, which may be identical to or different from each other, represent a hydrogen atom, a chlorine atom, a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent, etc., and may be joined to each other to form a ring; and V, W, X, Y and Z represent a carbon atom or a nitrogen atom, and 0 to 3 of any of V, W, X, Y and Z are nitrogen atoms which do not have the substituents of R3 to R7.