To provide a horizontal boring machine boring the side of a main pipe horizontally after the main pipe and a branch pipe are connected in the same plane.

This boring machine is provided with a driving shaft 10 movable vertically, a gear box 11 transmitting the driving force of the driving shaft 10 perpendicularly, a bending surface gear 12 connecting the driving shaft 10 and the input shaft of the gear box 11, a male screw 13, a power transmitting part 14, a saw part 15 boring the main pipe 1, an inner annular pipe 16, an elevating pipe 27 moving up and down with the driving shaft 10, a fixing part 17, an outer annular pipe 18, a set screw 19, a bearing 20 for facilitating the rotation of the driving shaft 10, a link 21 oscillatably connecting the lower part of the elevating pipe 27 and the gear box 11, and a driving means 22 driving the driving shaft 10.