A triple-pipeline type first outdoor unit 2 connected to three inter-unit pipelines 5 made up of a high-pressure gas pipe 7, a low-pressure gas pipe 6, and a fluid pipe 8 and a second outdoor unit 3 connected by two pipelines of a gas pipe 35 and a fluid pipe 36 are provided, in which a fluid pipe 36 of this second outdoor unit 3 is connected to the fluid pipe 8, while a gas pipe 35 of the second outdoor unit is selectively connected to the high-pressure gas pipe 7 or the low-pressure gas pipe 6 using a valve-element kit 50 having a four-way valve 51.