An air conditioner is provided. The air conditioner, which comprises a compressor, an outdoor heat exchanger, an indoor heat exchanger, a four-way valve, an accumulator, and an oil separator, and cools or heats a room by circulating a refrigerant. The air conditioner comprises a first block which is disposed on a first channel of the refrigerant between the oil separator and the four-way valve, and the first block is modular and includes a plurality of first control parts, and a second block which is disposed on a second channel of the refrigerant between the outdoor heat exchanger and the indoor heat exchanger, and the second block is modular and includes a plurality of second control parts.