The present invention provides a grass eliminator capable of remarkably reducing maintenance costs required for a purchase of components or supply of spare components by extending a replacement cycle of the components since a blade is easily replaced and a blade coupling ring member can be used in both direction. To achieve the purpose of the present, the grass eliminator has a blade mounting unit rotating by receiving power, and the blade mounting unit comprises an upper plate and a lower plate integrally assembled by being engaged with each other. The blade mounting unit includes: the lower plate having multiple mounting grooves formed on the upper surface in a radial direction and having a coupling protrusion to be adjacent to the mounting groove the upper plate having a cover groove formed on the lower surface to correspond to the mounting groove and the blade coupling ring member, wherein a horizontal ring at one end is fitted into the coupling protrusion and a vertical ring is mounted on the mounting groove in order for the vertical ring to be fixed by the cover groove when the upper plate is assembled. One side of a ring in the blade coupling ring member is open so that the blade on which a coupling hole is bored can be inserted and hung thereon. A horizontal ring and a vertical ring are symmetrically formed to be rotated at the angle of 90 degrees so that the horizontal ring and the vertical ring are changed and inserted into the coupling protrusion. According to technical composition, the blade can be easily changed only by separating the upper plate and the lower plate of the blade mounting unit since the blade coupling ring member is installed in order for the blade to be hung and installed. Especially, the blade coupling ring member is used in both directions, and the replacement cycle of the components is largely extended. Therefore, the maintenance costs required for the purchase of the components or the supply of the spare components can be remarkably
