PURPOSE: A yolk measuring method is provided to precisely measure various measurement elements of the yolk by analyzing an opened egg image. CONSTITUTION: A top camera obtains the top image of an opened egg on an opened egg plane board and a side camera obtains the side image of the opened egg(S210). The center and the measurement of the yolk of the opened egg are determined on the upper image(S220). The charge area of the yolk is obtained from the side image(S230). The upper boundary of the yolk is determined based on the area of the yolk(S240). A pixel height value is determined based on a vertical pixel coordinate difference between a reference line of the yolk height and the upper boundary of the yolk(S250). The yolk height is produced by the pixel height value and the measurement(S260).
