To improve the air conditioning efficiency in an engine driven air conditioner.

An air intake port 13a of an indoor heat exchanger 13 and a first underground pipe 30 are communicated with each other. The outside air is taken from one end 31 of the first underground pipe 30 to an air mixing device 22 through a burying part 32, mixed with the indoor air to be the mixed air, and introduced to the indoor heat exchanger from the air intake port 13a. As the heat exchange is executed when the outside air passes through the burying part 32 of the first underground pipe 30, the temperature change of the mixed air can be reduced, and the air conditioning efficiency can be improved.