(57) A negatively chargeable toner for a two-component magnetic developing agent obtainable by dispersing carbon black in a fixing resin medium wherein the fixing resin medium is a copolymerized resin or a resin composition comprising anionic polar groups and having an acid value from 4 to 30, and the carbon black has a pH less than 7, a ratio (7-pH)/specific surface area (m²/g) from 0.010 to 0.050 and is present in an amount from 4 to 15% by weight relative to the fixing resin. The toner maintains an electric charge in an amount sufficient for developing in the absence of a negative charge control agent. Hence, charge control agent does not migrate onto the carrier surfaces and hence the deterioration of charging properties by spent toner is reduced.