PURPOSE: A manhole cover is provided to adjust the height of a manhole simply and to keep the adjusted height of a manhole firmly. CONSTITUTION: The manhole cover(1) contains: a fixed frame(10) installed on an opening of a manhole and provided with a primary passage hole(12) and a projected screw(11); a height adjust ring(20) reciprocated along the fixed frame(10) according to rotational direction when rotating relatively against the fixed frame(10) and provided with a secondary passage hole(22), a height adjust hole(24) and a cogged joint(21); and a cover(30) contacted/supported to the cogged joint(21) of the height adjust ring(20) to open and close the secondary passage hole(22).
