PURPOSE: To surely prevent a lateral branch to be slipped off by allowing the latereral branch pipe to incline to the connection pipe part of a pipe joint when vibration such as earthquake occures.

CONSTITUTION: A pair of locking members 3, 4 provided with a grip portion 3a on the inner peripheral surface are fixed on the outer peripheral surface of a lateral branch pipe 2 in their pressure contact state, and fixing bolts 5, 5 for fixing both locking members 3, 4 are respectively inserted into insertion holes 8A, 8A of connection bolts 8, 8 fixed to a connection pipe part 10. The insertion hole 8a is so formed that its inside diameter may be slightly larger than that for insertion of the fixing bolt 5, and so that the fixing bolt 5 may be inclined within the fixed range in relation to the connection bolt 8.