PURPOSE: To determine the excess and shortage of refrigerant by comparing and calculating a superheat value, which is obtained by comparing a temperature detected by a temperature sensor and a temperature converted from a pressure detected by a pressure detection device, with a specified superheat value determined by an equipment model.

CONSTITUTION: A temperature sensor 14 is set to a suction pipe 8 of a compressor 2 with a clip 13 and a pressure detection device 10 is connected with a check valve 11. An indicated value is converted into temperature and read from a comparison table and this reading is input with a pressure input dial 18 of a refrigerant sealing quantity decision device. A detected value of a temperature sensor 14 and an input value of the pressure input dial 18 are compared and calculated by a first comparator 19. Then, a superheat value determined by equipment is input with a specified superheat value input dial 21, and an output value of the first comparator 19 and the specified superheat value are compared and calculated by a second comparator 22. When the quantity of refrigerant of equipment indicates a specified value, the output value of the second comparator 22 indicates 0. It is, therefore, possible to measure a proper amount of refrigerant definitely and easily.