Abstract: In order to develop further a portable motor or engine-driven cutting-off machine with a housing (100) and an arm (12) connected thereto, on which a parting-off tool (22) is detachably secured, which can be driven with the aid of a traction means gearing (13, 14, 28) with a power transmission shaft (14) disposed on the arm (12) in such a way that, by means of simple constructional modifications, the rigidity between housing and arm is enhanced and their disadvantageous vibration behavior during cutting operations is improved, it is proposed that the arm (12) and the housing (100) or a housing half (11) be fabricated in a one-piece construction.