To provide a portable cutting-off tool which can prevent the floating-up of a workpiece in cutting-off without damaging its housing.

The portable cutting-off tool 1 comprises a motor 3 retained in a housing 2 made of resin, a speed reducing mechanism for reducing the rotational speed of the motor 3, a cam rotationally driven via the speed reducing mechanism, and a rocking member to be rocked by being brought into contact with the cam; and cuts off a continuous thread stud W (material to be cut off) by pinching it by means of a movable cutting-off blade 26 provided on the rocking member and a fixed cutting-off blade 28 fixed to the housing 2. A round bar shape member 30 (reaction receiving portion) made of steel is provided in the housing 2 so as to support the continuous thread stud W at the portions except the portion to be cut-off.