PURPOSE: To make it easy to lift the side groove cover and move it in a condition wherein it is lifted.

CONSTITUTION: Vertical portions 11 of a self-standing frame means 10 fabricated substantially in the form of 'U' are bridged over a side groove and a rocking means 22 of a vertical movement means 20 mounted at a substantially central portion of the self-standing frame means 10 is rocked. A bar member 21 is thereby moved in the vertical direction to lift a side groove cover supported by a conveyance member 40 engaged with a lower end of the bar member 21 and bent end portions 51, 61 of hooks 50, 60 of the conveyance member 40. If, in this condition, the state of engagement between the conveyance member 40 and the bar member 21 of the vertical movement means 20 at the lower end thereof is released, the vertical movement means 20 is separated from a conveyance means 30. Therefore, if both grip portions 41 of the conveyance member 40 constituting the conveyance means 30 are gripped and are moved, then it will be possible to move the side groove cover to a prescribed position.