To provide an earth drill having a pressing means which is easy in building a surface layer casing and free from misalignment, a jig for surface layer casing, and a press-in method of the surface layer casing.

A jig 15 to be placed on and fixed to an upper surface of a surface layer casing 13 is provided, and the jig 15 connected to a kelly-bar 5 in an attachable/detachable manner. The jig 15 is placed on a surface layer casing 13, and the surface layer casing 13 is pressed in by the kelly-bar 5 of the earth drill. The kelly-bar 13 is pressed in by connecting the jig 15 to the surface layer casing 13 while the surface layer casing 13 is rotated by the kelly- bar 5.