Abstract: A method of measuring a Stockigt sizing degree of a paper or hoard is provided. The method includes: placing a paper or board, to which FeCl3 (II) is dropped or applied, on NH4SCN solution; sequentially capturing, by using a camera, a process of forming reddish brown Fe(SCN)3 wile the FeCl3 (II) meets the NH4SCN solution penetrating in a thickness direction of the specimen, and recording RGB values of droplet image of the reddish brown Fe(SCN)3; converting the RGB values into HSV values; recording hue (H) value of the HSV values with respect to time; and checking a point where a differentiation value of the H value recorded with respect to time becomes maximum.