To provide an internal pipeline opening device capable of structuring an opening head or a head body to be compact and having little possibility of causing a failure in the opening operation.

The internal pipeline opening device is constituted of a body moving in a sewage pipe 3 and the opening head 13 attached to the body. The opening head 13 is constituted of the head body 33 having a driving hydraulic swing motor 45, an opening vehicle 35 having an opening drill 41 provided on the head body 33 to be movable in the radial direction of the sewage pipe 3, and a swing arm 51 having a front end rotatably and slidably connected with the vehicle 35 and having a base end 53 attached to a rotary output shaft of the motor 45. The driving hydraulic swing motor 45 is driven and the swing arm 51 swings with the base end 53 as the center, whereby the vehicle 35 moves in the radial direction of the sewage pipe 3.