An image forming apparatus, comprising: a plurality of image carriers (40; 40Y, 40M, 40C, 40K) each configured to bear a toner image; an endless belt configured to sequentially contact a front surface thereof with the plurality of image carriers to form respective transfer nips; and a plurality of bias applying rollers (62; 62Y; 62M, 62C, 62K) provided at positions corresponding to the respective image carriers (40; 40Y, 40M, 40C, 40K), each bias applying roller (62; 62Y; 62M, 62C, 62K) being configured to apply a transfer bias to a back surface of the endless belt to transfer the toner image from the image carrier to the endless belt, wherein the toner image is formed of a toner having, a mother particle including a binder resin and a colorant, and an external additive and having an external additive burial rate of not less than 40 percent, the burial rate X being defined by the formula X(%) = {(Y1-Y2)/ Y1}x100, where Y1 is the BET specific surface area in cm 2 /g before the embedding of additive and Y2 is the BET specific surface area in cm 2 /g after the embedding of additive; wherein each bias applying roller (62; 62Y; 62M, 62C, 62K) is located so as to satisfy the following relationship L > A / 2 + B / 2 + C where A is a diameter of the image carrier (40; 40Y, 40M, 40C, 40K), B is a diameter of the bias applying roller (62; 62Y; 62M, 62C, 62K), C is a thickness of the endless belt, and L is a distance between axis centers of the image carrier (40; 40Y, 40M, 40C, 40K) and the bias applying roller (62; 62Y; 62M, 62C, 62K), on a virtual plane perpendicular to an axis direction of the image carrier (40; 40Y, 40M, 40C, 40K), wherein the bias applying roller (62; 62Y; 62M, 62C, 62K) is placed downstream of the image carrier (40; 40Y, 40M, 40C, 40K) in a moving direction of the endless belt, characterized in that: each of the bias applying rollers (62; 62Y, 62M, 62C, 62K) is placed so as to satisfy the following relationship D < Wd / 10 where D is a distance between the axis centers of each of the image carriers (40; 40Y, 40M, 40C, 40K) and the corresponding bias applying roller (62; 62Y, 62M, 62C, 62K) in a moving direction of the endless belt and Wd is a distance between centers of the image carriers (40; 40Y, 40M, 40C, 40K). a plurality of image carriers (40; 40Y, 40M, 40C, 40K) each configured to bear a toner image; an endless belt configured to sequentially contact a front surface thereof with the plurality of image carriers to form respective transfer nips; and a plurality of bias applying rollers (62; 62Y; 62M, 62C, 62K) provided at positions corresponding to the respective image carriers (40; 40Y, 40M, 40C, 40K), each bias applying roller (62; 62Y; 62M, 62C, 62K) being configured to apply a transfer bias to a back surface of the endless belt to transfer the toner image from the image carrier to the endless belt, wherein the toner image is formed of a toner having, a mother particle including a binder resin and a colorant, and an external additive and having an external additive burial rate of not less than 40 percent, the burial rate X being defined by the formula X(%) = {(Y1-Y2)/ Y1}x100, where Y1 is the BET specific surface area in cm 2 /g before the embedding of additive and Y2 is the BET specific surface area in cm 2 /g after the embedding of additive; wherein each bias applying roller (62; 62Y; 62M, 62C, 62K) is located so as to satisfy the following relationship L > A / 2 + B / 2 + C where A is a diameter of the image carrier (40; 40Y, 40M, 40C, 40K), B is a diameter of the bias applying roller (62; 62Y; 62M, 62C, 62K), C is a thickness of the endless belt, and L is a distance between axis centers of the image carrier (40; 40Y, 40M, 40C, 40K) and the bias applying roller (62; 62Y; 62M, 62C, 62K), on a virtual plane perpendicular to an axis direction of the image carrier (40; 40Y, 40M, 40C, 40K), wherein the bias applying roller (62; 62Y; 62M, 62C, 62K) is placed downstream of the image carrier (40; 40Y, 40M, 40C, 40K) in a moving direction of the endless belt, characterized in that: each of the bias applying rollers (62; 62Y, 62M, 62C, 62K) is placed so as to satisfy the following relationship D < Wd / 10 where D is a distance between the axis centers of each of the image carriers (40; 40Y, 40M, 40C, 40K) and the corresponding bias applying roller (62; 62Y, 62M, 62C, 62K) in a moving direction of the endless belt and Wd is a distance between centers of the image carriers (40; 40Y, 40M, 40C, 40K). each of the bias applying rollers (62; 62Y, 62M, 62C, 62K) is placed so as to satisfy the following relationship D < Wd / 10 where D is a distance between the axis centers of each of the image carriers (40; 40Y, 40M, 40C, 40K) and the corresponding bias applying roller (62; 62Y, 62M, 62C, 62K) in a moving direction of the endless belt and Wd is a distance between centers of the image carriers (40; 40Y, 40M, 40C, 40K).