An air conditioner comprising: first and second compressors (520, 540); an accumulator disposed at an inlet side of the first and second compressors (520, 540); a main suction passage connected with an outlet of the accumulator; first and second suction passages (820,840) branched from the main suction passage to extend to the first and second compressors (520, 540), to guide suction of a refrigerant into the first and the second compressors (520, 540); first and second oil separators (562, 582) disposed at an outlet side of the first and the second compressor (520, 540), respectively and configured to separate oil from the first and the second compressors (520, 540); an oil level sensor (522, 542) disposed in the first or second compressor (520, 540) to detect whether the compressor lacks oil; a first return passage extending from the first oil separator toward the first suction passage, to introduce the oil separated from the first oil separator into the first compressor and in which a second valve is installed; a second return passage extending from the second oil separator toward second suction passage, to introduce the oil separated from the second oil separator into the second compressor and in which a third valve is installed, characterized in that: the first return passage includes a branch part, a distribution return passage is branched from the branch part of the first return passage to be connected to the main suction passage; and a first valve is disposed in the distribution return passage. first and second compressors (520, 540); an accumulator disposed at an inlet side of the first and second compressors (520, 540); a main suction passage connected with an outlet of the accumulator; first and second suction passages (820,840) branched from the main suction passage to extend to the first and second compressors (520, 540), to guide suction of a refrigerant into the first and the second compressors (520, 540); first and second oil separators (562, 582) disposed at an outlet side of the first and the second compressor (520, 540), respectively and configured to separate oil from the first and the second compressors (520, 540); an oil level sensor (522, 542) disposed in the first or second compressor (520, 540) to detect whether the compressor lacks oil; a first return passage extending from the first oil separator toward the first suction passage, to introduce the oil separated from the first oil separator into the first compressor and in which a second valve is installed; a second return passage extending from the second oil separator toward second suction passage, to introduce the oil separated from the second oil separator into the second compressor and in which a third valve is installed, characterized in that: the first return passage includes a branch part, a distribution return passage is branched from the branch part of the first return passage to be connected to the main suction passage; and a first valve is disposed in the distribution return passage. the first return passage includes a branch part, a distribution return passage is branched from the branch part of the first return passage to be connected to the main suction passage; and a first valve is disposed in the distribution return passage.