To provide a cutter device for a fluid pipe which can discharge cutting chips efficiently to the outside so as to prevent the cutting chips scattered just after cutting from infiltrating into the fluid pipe from a cut port.

This cutter device cuts off a fluid pipe 1 by inserting a cutting toll 2 integrally rotated with a rotary sleeve 3 from a work hole 3a, the work hole 3a is extended to the vicinity of a cut off part of the fluid pipe 1, and cutting chips are discharged together with a fluid to outside the rotary sleeve 3 through the work hole 3a at time of cutting.