To provide an underground boring vehicle capable of easily changing the bearing of a drill relative to a movable arm, moving the directional attitude of a drill more flexibly, and increasing a workability and controllability for boring.

A disk 7c is installed tiltably at the tip of movable arms 12 and 13 installed on a swing table 11 of a crawler vehicle 10 through a link 20 and a cylinder 19, a disk 70a of the same diameter as the disk 7c is overlapped on the disk 7c, and bolts are inserted into the bolt holes of these disks at a specified angular phase to connect them to each other. The disk 7a on the upstream side is fixed to the middle position of a frame 1 of an underground boring device B which feeds a drill into the ground while rotating the drill. The direction of the drill is changed at an angular phase at which the pair of disks are connected to each other.