A developing roller includes a core metal and an elastic layer formed on an outer circumference of the core metal. An outermost surface of the developing roller is roughened. A difference between a maximum value and a minimum value of an indentation power of the outermost surface is 10% to 21%, wherein the indentation power is measured by a micro-indentation test at 120 locations spaced 3 degrees apart on a circumference of the developing roller, which is at a center of the developing roller with respect to a longitudinal direction. A developing device and an image forming apparatus each include the developing roller.