PURPOSE: To provide an air conditioner capable of reducing a state in which all functions are stopped under an operation of a protection device accompanied by a rapid variation of a refrigerant pressure.

CONSTITUTION: An indoor device 20 is provided with a valve travel changing range transmitter 18 for transmitting an indoor expansion valve travel changing range determined by a valve travel changing range determination means 16. An outdoor device 11 is provided with a valve travel changing range receiver 10 for receiving an indoor expansion valve travel changing range and a capability changing range correction means 8 for correcting a compressor capability changing range determined by a capability changing range determining means 7 in response to an indoor expansion valve opening degree changing range.