A drive apparatus for a construction machine, comprising: an electric motor serving as a drive source and having a motor shaft and a motor housing ; and a speed reducer that includes a speed reducer output shaft for transmitting a force to a driven portion , a speed reduction mechanism that reduces speed of a rotation force of the motor shaft and transmits the reduced rotation force to the speed reducer output shaft , and a casing surrounding a speed reducer chamber in which the speed reduction mechanism is housed and lubricating oil (O) is injected, and that is provided below the electric motor such that the motor shaft and the speed reducer output shaft are arranged along a same line, characterized in that an interior of the motor housing communicates with the speed reducer chamber such that a flow of air between the speed reducer chamber and the interior of the motor housing is permitted while limiting inflow of the lubricating oil into the interior of the motor housing from the speed reducer chamber , and an air breather for opening the interior of the motor housing to the atmosphere is provided in the motor housing , wherein the electric motor includes a motor side partition wall that partitions the interior of the motor housing from the speed reducer chamber , the motor shaft penetrating the motor side partition wall , and the motor side partition wall is provided with a motor side shaft sealing mechanism that limits a flow of the lubricating oil between the motor side partition wall and the motor shaft , and a motor side air passage that permits a flow of air between the speed reducer chamber and the interior of the motor housing while limiting inflow of the lubricating oil (O) into the interior of the motor housing from the speed reducer chamber , the motor side air passage is provided between the motor side shaft sealing mechanism and the motor shaft . an electric motor serving as a drive source and having a motor shaft and a motor housing ; and a speed reducer that includes a speed reducer output shaft for transmitting a force to a driven portion , a speed reduction mechanism that reduces speed of a rotation force of the motor shaft and transmits the reduced rotation force to the speed reducer output shaft , and a casing surrounding a speed reducer chamber in which the speed reduction mechanism is housed and lubricating oil (O) is injected, and that is provided below the electric motor such that the motor shaft and the speed reducer output shaft are arranged along a same line, characterized in that an interior of the motor housing communicates with the speed reducer chamber such that a flow of air between the speed reducer chamber and the interior of the motor housing is permitted while limiting inflow of the lubricating oil into the interior of the motor housing from the speed reducer chamber , and an air breather for opening the interior of the motor housing to the atmosphere is provided in the motor housing , wherein the electric motor includes a motor side partition wall that partitions the interior of the motor housing from the speed reducer chamber , the motor shaft penetrating the motor side partition wall , and the motor side partition wall is provided with a motor side shaft sealing mechanism that limits a flow of the lubricating oil between the motor side partition wall and the motor shaft , and a motor side air passage that permits a flow of air between the speed reducer chamber and the interior of the motor housing while limiting inflow of the lubricating oil (O) into the interior of the motor housing from the speed reducer chamber , the motor side air passage is provided between the motor side shaft sealing mechanism and the motor shaft . <EOS>