The present invention provides a binder resin that is used for an electrophotographic toner, an electrophotographic toner using the same, and a manufacturing method thereof, as well as an electrophotographic developer and an image forming method. The binder resin includes a rare earth element in a range of about 1 to 10000 ppm and is preferably made of a polyester resin. The polyester resin is preferably synthesized from from an acid unit having a dicarboxylic acid group and an alcohol unit having a diol group by use of a non-homogeneous catalyst in which a rare earth metal triflate or a rare earth metal triflylimide is carried on a carrier.