A unitary air conditioner includes a thermostat for generating an operation signal, an outdoor equipment operated according to an operation signal of the thermostat, an indoor equipment whose indoor fan is driven according to an operation signal of the thermostat, and an indoor fan control unit for increasing air volume after the indoor fan is driven at a rated air volume. After being driven at a rated air volume, the indoor fan is driven at an air volume higher than the rated air volume, thereby realizing a power saving operation with good energy efficiency.