To provide an outdoor unit for an air conditioner, which realizes the equalizing of oil levels in a plurality of compressors.

First to third communicating tubes 101-103 are provided with a plurality (2-3) of curved units near the connecting site to respective compressors 3-5 and are formed so as to retain horizontal or descending condition from the connecting sites of respective compressors 3-5 to a joining unit or a T-joint (not shown in a diagram). When oil levels OL1-OL3 have become uneven in respective compressors 3-5, refrigerating machine oil is moved through a level equilibrium tube during stopping of the air conditioner whereby the unevenness is eliminated gradually. On the other hand, an outdoor side ECU drives the first - third compressors 3 sequentially for a short period of time at every given times to contrive the equilibrium of the oil levels OL1-OL3 forcibly.