PURPOSE: To obtain an inexpensive controller which can be easily set without erroneous setting by providing a self-address setter, a connecting tube number setter, and indoor unit capacity setter, fixing maximum indoor air conditioning capacity per one connecting tube, and so setting that the tubes are combined with serial tube numbers.

CONSTITUTION: A self-address setter 12, a connecting tube number setter 13 and an indoor unit capacity setter 14 are provided in indoor units 11a-11h, and the capacities of the units 11a-11h are set by the setter 14. If the indoor unit capacity exceeds the indoor maximum capacity of one tube connection port, a solenoid valve provided in the connecting tube is so controlled to be opened and closed that the tubes of serial numbers are combined until the indoor unit capacity falls within the maximum capacity. If the connected tube numbers are set by the setter 13 of the units 11a-11h and combined, the smallest tube number is set. The setter 12 so sets as not to duplicate self-addresses for individually identifying the units 11a-11h.