Abstract: The invention relates to a device for locking a cover (10) of a manhole top to the frame thereof, said device comprising at least one locking means (16?, 18?) which is provided on the cover (10) and comprises at least two interspaced, adjacent spring arms (18) that are respectively provided with an engaging section (18a?). Said sections (18a) can be engaged with a part (6) of the frame and held on the spring arms (18) in an elastic manner in such a way that they can be displaced in relation to the adjacent section of the periphery of the cover (10) at an angle smaller than a right angle. The invention is characterised in that a blocking device (40) is used to block the displacement of the engaging sections (18a) as required.