PURPOSE: To cut off and remove each of pipes crossed with one another in a narrow space, by previding a clamping mechanism and a cutting-off section vertical moving mechanism which has a metal saw.

CONSTITUTION: A device for cutting off pipes of a nuclear reactor or the like comprises a cutting-off mechanism 30 and a clamping mechanism 20, which are vertically moved together. A shaft 36 is provided in a piston 35 to make the cutting-off device compact. Since a metal saw 38 is installed in an intermediate part, the cutting-off mechanism 30 and the clamping mechanism 20 can be inserted into each narrow gap between the regularly and closely collected pipes 8aW8h. Because the cutting-off mechanism 30 does not need to be revolved as in conventional cases, cutting-off work is facilitated. Each of the pipes crossed with one another in a narrow space can thus be smoothly cut off and removed.