To calculate a medicine fee without contradiction without regard to the high/low of tow kinds of medicine charges by calculating a health insurance charging amount based on a medicine charge B when a medicine charge (medicine change A) common to each group of a prescribed medicine is high than the medicine charge (medicine change B) given to individual medicines and based on the medicine charge A when the medicine charge A is lower than the charge B.

When an operator inputs prescription data from a key board 17 by referring to a prescription data, a control part 12 temporarily stores it in a memory 11 and retrieves a medicine code file 21 by using an inputted medicine code. Then, the charges A and B are sent to a medicine charge comparing part 13 from read code data to compare their high/low. As a result, when the charge A is higher tan the charge B, namely when a referring price is higher than an actual price, the part 12 instructs a first calculating part 14 to calculate a health insurance charging amount and a patient's sharing amount based on the charge B. When actual price is higher than the referring price, the part 12 instructs a second calculating part 15, which calculates the health insurance charging amount and the patient's sharing amount based on the charge A.