To provide a milling cut-off device with an internal bead cutter of light weight and simple structure, capable of being easily controlled.

An inlet side-clamp device 11, a milling-type piece cutter 12, an outlet side-clamp device 13 and the internal bead cutter 14 are mounted on a traveling truck 3. Pinch rollers 15 for accelerating a leading cut pipe 1a to a line base on the outlet side of the internal bead cutter 14 on the traveling truck 3 are mounted on the ground. The internal bead cutter 14 is provided with a cutter having a fixed blade 20 and a laterally moving blade 21, and a sensor mounted in the downstream of the cutter for detecting a rear end of the leading pipe 1a.