To amplify the vertical motion of an oscillating member 24 by means of a chain hung across a pair of sprockets 28, 29 rotatably attached to the oscillating member 24 for transmission of the vertical motion to a boring head, by providing the oscillating member 24 so as to move up and down on a body 23 mounted on the front end of an intra-pipeline moving means 2, and a boring head 33 on the oscillating member 24 so as to move up and down.

An excessively large cylinder 25 is not needed so as to downsize this apparatus, and a boring jig 34 is moved up by a stroke twice as much as that of the cylinder 25, so that the apparatus can be applied to a pipeline having a wide range of bore, and the boring jig 34 is deeply inserted into a branch pipe, and an adhesive which flows into the branch pipe and is hardened is bored to be removed positively, thus it is possible to connect the branch pipe to a main pipe positively.