An engine-driven working machine wherein a cooling fan is provided in an inside of an outer case, an inverter is provided at a suction side of the cooling fan, and a fuel tank is provided over the inverter, the engine-driven working machine comprises: an intake port that is formed in the outer case in a lower part near a wall portion of the fuel tank; and an air guide passage that is formed by a bottom portion of the fuel tank, the bottom portion of the fuel tank has a tank inclined portion inclining with a falling gradient toward the inverter from the intake port; an operation section that is provided under the bottom portion and that includes an operation panel and equipment provided on the operation panel; and a cover that covers the equipment, the cover has a cover rear wall that is disposed behind the operation panel and a cover top portion that extends toward the operation panel from an upper end of the cover rear wall, the bottom portion of the fuel tank is disposed over the cover top portion with a space left with respect to the cover top portion; and the inverter is disposed in a state where a radiating surface of the inverter faces the cover rear wall and the radiating surface is disposed with a space left with respect to the cover rear wall, characterized in that the intake port is formed in the outer case, as a single input port, the bottom portion of the fuel tank has a bend portion that extends in a bent shape from the lower end of the tank inclined portion toward an upper end of a radiating surface of the inverter, a lower end portion of the bend portion is adjacent to the upper end of the radiating surface of the inverter, and is disposed in a same plane as the upper end, whereby the cooling air that is guided along the bottom portion is guided to the radiating surface of the inverter. an intake port that is formed in the outer case in a lower part near a wall portion of the fuel tank; and an air guide passage that is formed by a bottom portion of the fuel tank, the bottom portion of the fuel tank has a tank inclined portion inclining with a falling gradient toward the inverter from the intake port; an operation section that is provided under the bottom portion and that includes an operation panel and equipment provided on the operation panel; and a cover that covers the equipment, the cover has a cover rear wall that is disposed behind the operation panel and a cover top portion that extends toward the operation panel from an upper end of the cover rear wall, the bottom portion of the fuel tank is disposed over the cover top portion with a space left with respect to the cover top portion; and the inverter is disposed in a state where a radiating surface of the inverter faces the cover rear wall and the radiating surface is disposed with a space left with respect to the cover rear wall, characterized in that the intake port is formed in the outer case, as a single input port, the bottom portion of the fuel tank has a bend portion that extends in a bent shape from the lower end of the tank inclined portion toward an upper end of a radiating surface of the inverter, a lower end portion of the bend portion is adjacent to the upper end of the radiating surface of the inverter, and is disposed in a same plane as the upper end, whereby the cooling air that is guided along the bottom portion is guided to the radiating surface of the inverter.