SMALL BORE PUSHER

PROBLEM TO BE SOLVED: To form a bore of a roughly similar diameter to an outer diameter of a buried pipe, push the buried pipe without deteriorating construction efficiency even with a conglomerate bed or soil quality of a high N-value, return a head pipe to a starting vertical shaft, and install the head pipe to an original position after returning the head pipe for enabling pushing or a long distance. SOLUTION: An outer diameter of a head pipe is smaller than an inner diameter of a buried pipe, it can be parted to a front drum and a back drum 4b, and the front drum and the back drum 4b are connected to each other by an oscillation jack 9. An outer diameter of a cutter head 7 provided on a tip of the front drum is smaller than the inner diameter of the buried pipe, and the front drum is oscillated by the oscillation jack 9 in such a way that an outer diameter of a bored track is roughly similar to an outer diameter of the buried pipe. The head pipe and the cutter head 7 are recovered through the buried pipe into a starting vertical shaft.