PURPOSE: To control a desired traveling direction by advancing a hose as the boring of a tubular body proceeds and providing a unit for measuring the differential static pressure of liquid filling the hose.

CONSTITUTION: When a hose 6 moves in a tunnel 3 while following up a tubular body 1 for tunnel boring and the relative height of tubular body 1, that is relative height of the tunnel 3, changes corresponding to a pressure sensor 8, static pressure acting on the sensor 8 is also varied to provide a direct measure of relative height between the opposite ends of hose 6. Static pressure from the sensor 8 is converted through a numeric measurement converter 10 and fed to a display/memory 9. Furthermore, the tubular body 1 is provided with a program unit 14 for storing a specified digging course and when the unit 14 is connected with a controller 12, a digging course can be programmed previously. Since numeric values of the converter 10 and a course sensor 11 are transmitted, as correction values, to the controller 12, the course can be controlled and corrected while digging.