Lawn mower robot

A lawn mower robot includes: an outer cover; an inner body accommodated inside the outer cover and having a plurality of wheels on both side surfaces for traveling; a rotating plate rotatably mounted on a bottom surface of the inner body; a plurality of blades rotatably mounted on the rotating plate to cut grass; a height adjustment unit to adjust height of the blades; and a height display unit to display the blade height, wherein the height display unit includes: an inner cover mounted on an upper portion of the outer cover; a display window formed through one side of the inner cover; and a ruler having numerals on an upper surface to display the height of the blades, and mounted inside the inner body to be movable up and down and back and forth in correspondence to movement of the height adjustment unit.