To provide an air-conditioner that can secure a proper amount of oil required by each compressor when a plurality of compressors are operated either simultaneously or individually.

First, second, and third compressors 1a, 1b, and 1c are connected to first, second, and third oil separators 8a, 8b, and 8c in parallel with the discharge pip of each compressor. A fourth oil separator 9b is connected between the oil separators 8a, 8b, and 8c and a four-way valve 8 via first, second, and third on/off valves 9a, 9b, and 9c. Each oil return pipe of the first, second, and third oil separators 8a, 8b, and 8c is connected each intake pipe of the first, second, and third compressors 1a, 1b, and 1c via fourth, fifth, and sixth on/off valves 10a, 10b, and 10c. In the oil return pipe of fourth oil separator 8d, seventh, eighth, and ninth on/off valves 11a, 11b, and 11c are connected to each intake pipe of the compressor. Oil level sensors 12a, 12b, 12c, 12d, 12e, and 12f for detecting an oil level are provided in the first, second, and third compressors 1a, 1b, and 1c. The opening and the closing of the seventh, eighth, and ninth on/off valves 11a, 11b, and 11c are controlled according to the detected oil level.