An air conditioner comprising: an indoor unit air-conditioning indoor air; and an outdoor unit connected to the indoor unit through a refrigerant tube, wherein the outdoor unit comprises: a compressor compressing a refrigerant; and an oil separator comprising a housing defining an outer appearance thereof having a first through hole disposed in a bottom surface of the housing and a second through hole defined in a side surface of the housing; and a plurality of oil recovery tubes (331, 332) introducing oil into the compressor and including a first recovery tube connected with the first through hole to provide a moving path of the oil in the housing and a second recovery tube disposed relatively above the first recovery tube and connected with the second through hole to provide a moving path of the oil in the housing; and characterized in that the air conditioner further comprises: an oil valve provided in the second recovery tube to guide a movement direction of the oil, wherein the oil in suctioned into one recovery tube of the first and second recovery tubes (331, 332) when the oil valve is opened, and the oil is suctioned into the other recovery tube of the first and second recovery tubes (331, 332) when the oil valve is closed; and a combining part is disposed on a position at which the first and second recovery tubes (331, 332) communicate with each other, the oil passing through the first recovery tube and the oil passing through the second recovery tube being configured to be mixed with each other in the combining part; and a distance between the bottom surface of the housing and the combining part is greater than or equal to a distance between the bottom surface of the housing and an inlet of the second recovery tube, to prevent the oil flowing through the second recovery tube from flowing backward. an indoor unit air-conditioning indoor air; and an outdoor unit connected to the indoor unit through a refrigerant tube, wherein the outdoor unit comprises: a compressor compressing a refrigerant; and an oil separator comprising a housing defining an outer appearance thereof having a first through hole disposed in a bottom surface of the housing and a second through hole defined in a side surface of the housing; and a compressor compressing a refrigerant; and an oil separator comprising a housing defining an outer appearance thereof having a first through hole disposed in a bottom surface of the housing and a second through hole defined in a side surface of the housing; and a plurality of oil recovery tubes (331, 332) introducing oil into the compressor and including a first recovery tube connected with the first through hole to provide a moving path of the oil in the housing and a second recovery tube disposed relatively above the first recovery tube and connected with the second through hole to provide a moving path of the oil in the housing; and characterized in that the air conditioner further comprises: an oil valve provided in the second recovery tube to guide a movement direction of the oil, wherein the oil in suctioned into one recovery tube of the first and second recovery tubes (331, 332) when the oil valve is opened, and the oil is suctioned into the other recovery tube of the first and second recovery tubes (331, 332) when the oil valve is closed; and a combining part is disposed on a position at which the first and second recovery tubes (331, 332) communicate with each other, the oil passing through the first recovery tube and the oil passing through the second recovery tube being configured to be mixed with each other in the combining part; and an oil valve provided in the second recovery tube to guide a movement direction of the oil, wherein the oil in suctioned into one recovery tube of the first and second recovery tubes (331, 332) when the oil valve is opened, and the oil is suctioned into the other recovery tube of the first and second recovery tubes (331, 332) when the oil valve is closed; and a combining part is disposed on a position at which the first and second recovery tubes (331, 332) communicate with each other, the oil passing through the first recovery tube and the oil passing through the second recovery tube being configured to be mixed with each other in the combining part; and a distance between the bottom surface of the housing and the combining part is greater than or equal to a distance between the bottom surface of the housing and an inlet of the second recovery tube, to prevent the oil flowing through the second recovery tube from flowing backward.