a main-body casing;

a worktop having an open-close operability provided at a top of the main-body casing;

an introduction area through which the material powder is introduced into the main-body casing;

a classifying means having a classifying rotor by means of which fine powder and ultrafine powder having a particle diameter not larger than a stated particle diameter are continuously removed from the material powder introduced into the main-body casing;

a fine-powder discharge area through which the fine powder and ultrafine powder removed by the classifying means are discharged out of the main-body casing;

a surface modifying means having a dispersing rotor and a liner such that particles contained in a finely pulverized product, from which the fine powder and ultrafine powder have been removed, are subjected to a surface modification treatment using a mechanical impact force;

a cylindrical guide means for forming a first space and a second space in the main-body casing; and

a toner particle discharge area through which the toner particles subjected to the surface modification treatment by the dispersing rotor and the liner are discharged out of the main-body casing,

wherein the first space, which is provided between an inner wall of the main-body casing and an outer wall of the cylindrical guide means, is a space through which the material powder and the toner particles, which have been surface-modified, are guided to the classifying rotor,

wherein the second space is a space in which the material powder, from which the fine powder and ultrafine powder have been removed, and the particles, which have been surface-modified, are treated by the dispersing rotor,

wherein, in the surface modifying apparatus, the material powder introduced into the main-body casing through the introduction area is led into the first space, the fine powder and ultrafine powder having the particle diameter not larger than the stated particle diameter are removed by the classifying means and continuously discharged out of the apparatus, and the material powder, from which the fine powder and ultrafine powder have been removed, is moved to the second space and treated by the dispersing rotor and the liner to carry out the surface modification treatment of the toner particles contained in the material powder, and the material powder containing the toner particles that have been surface-modified are again circulated to the first space and the second space to repeat the classification and the surface modification treatment, to thereby obtain toner particles from which the fine powder and ultrafine powder having the particle diameter not larger than the stated particle diameter have been removed at a quantity not more than a stated quantity and which have been surface-modified,

wherein the dispersing rotor has, at a top surface thereof, a plurality of rectangular disks,

wherein the dispersing rotor has an outer diameter of 120 mm or more,

wherein a minimum gap between the dispersing rotor and the liner is from 1.0 mm to 3.0 mm, and

wherein a number n of the rectangular disks provided at the top surface of the dispersing rotor and an external diameter D of the dispersing rotor satisfy a relationship of expression (1):

π×D/n<95.0 (mm)  (1).