A motor driving device and an air conditioner including the same are disclosed. The motor driving device includes a rectifier to rectify input AC power, a boost converter for boosting the rectified power from the rectifier, a first capacitor to store a pulsating voltage from the boost converter, a first inverter for outputting, to a compressor motor, AC power transformed using a voltage across the first capacitor, a second capacitor to store the rectified power from the rectifier, a second inverter for outputting, to a first fan motor, AC power transformed using a voltage across the second capacitor, and a voltage dropper to drop the voltage across the second capacitor, and to output the dropped voltage. In accordance with this configuration, the compressor motor and fan motor can be driven, using the same input AC power, even though the motor driving device uses a low-capacitance capacitor.