An electrophotographic developer including: magnetic particles, and a toner containing toner particles charged with the magnetic particles and having a particle diameter distribution, wherein the toner exhibits cumulative toner weight distributions of both square of charge amount q.sup.2 [C.sup.2] and attachment force F [N] per particle with respect to a representative toner particle diameter in the particle diameter distribution, giving a linear approximation of plots of the attachment force F [N] versus the square of charge amount q.sup.2 [C.sup.2] per particle at a plurality of corresponding cumulative toner weight ratios, and the linear approximation satisfies a slope of the linear approximation of from 5.times.10.sup.20 to 3.times.10.sup.22 and a squared multiple correlation coefficient (R.sup.2) of 0.6 or more. As a result, the developer allows good control of transferability under the control of an electric field and allows a reduction in transfer residual amount of the toner.