A ground-boring apparatus for boring the ground within a casing tube, which is driven into the ground by a casing tube pusher machine to prevent the surrounding soil from collapsing into a to be formed hole. The soil removed by an extensible kelly bar to be suspended by a movable crane, a boring bucket attached to the lower end of the kelly bar, a supporting frame unit to be placed on the casing tube for holding the kelly bar rotatably about its vertical axis, hydraulic motors provided on the supporting frame unit for turning the kelly bar about its vertical axis, and clamping devices for joining the supporting frame unit and the casing tube.