Abstract: A refrigerant refill amount calculating apparatus is provided with concentration measuring units for measuring component ratios X1:Y1:Z1 of fluorocarbon S contained in a refrigerating machine, and a calculation processing unit. The calculating unit calculates additional filling amounts of respective refrigerant components which are required to fill fluorocarbon having a defined amount “A” in accordance with defined component ratios X:Y:Z within the refrigerating machine 2 based upon an additional filling amount Xa of a refrigerant component which has been additionally filled into the refrigerating machine, and a change amount of component ratios X1:Y1:Z1, X2:Y2:Z2 which have been measured before and after the refrigerant component was filled. Refill amounts of refrigerant components can be easily calculated in a correct manner.