PURPOSE: To enhance the performance of a horizontal hole augering machine used to dig a horizontal hole in underground embedding and crossing work, such as sewerage, water supply and telephone cable.

CONSTITUTION: This invention relates a horizontal hole augering machine in which a cylinder-shaped tuyere 16 is laid out in front of a pipe member 14 to be pushed into a horizontal hole by way of a partition wall 15 while a rotary cutter 25 is installed to the front of the tuyere 16, a water-sealed type differential epicyclic reduction gear 55 is installed inside the tuyere 16 in front of the partition wall 15. An output shaft of a motor 56 installed to the rear side of the partition wall 15 is connected to an input shaft 57 of the water-sealed type differential epicyclic reduction gear 55 by way of the partition wall 15 where a rotary shaft output part of the water-sealed differential epicyclic reduction gear 55 is connected to the rotary cutter 25.