To perform vertical hole boring work at a job site limited in an upper space, for example, the inside of a tunnel.

This vertical hole boring device is provided with a guide casing fastened and fixed to an upper part of the ground to be excavated, a slide casing arranged in the guide casing so as to be capable of freely protruding and retreating, an extending/contracting device for extending and contracting these casings and a vertical hole boring machine body being supported by an inner wall of the slide casing and having a cutting machine in a lower part to bore a vertical hole by the cutting machine.