A part replacement method for replacement of a part of a refrigeration cycle apparatus includes a refrigerant circuit in which a flammable refrigerant is circulated and a container connecting device for controlling the refrigerant such that the refrigerant is allowed to flow out of the refrigerant circuit. The method includes a refrigerant recovery step of allowing the refrigerant to flow out of the refrigerant circuit through the container connecting device, a pressure reduction step of connecting a pressure reducing device to the container connecting device to reduce a pressure in the refrigerant circuit until the pressure in the refrigerant circuit reaches a set pressure or a setting time is reached, and a part replacement step of removing the part from the refrigerant circuit by heating to replace the part.