A portable power working machine (10) is disclosed, which is capable of effectively improving the performance thereof to cool the internal combustion engine (20), and also capable of preventing an air cleaner (30) of the air intake system of the internal combustion engine (20) from being clogged with dust. This portable power working machine is characteristic in that it comprises a guiding wall (28) disposed on one side of a main housing (12) and at a location rear to a cooling fan (25) and projected inward therefrom for guiding cooling air toward the cylinder (21) of the internal combustion engine (20); an intake passageway (50) formed at a location rear to the cooling fan (25) for introducing air into an air-intake system (30, 34, 35) of the internal combustion engine (20); and an air-intake port (55) for the intake passageway (50), the air-intake port (55) being positioned in the vicinity of a root portion (28a) of the rear face of the guiding wall (28).