[Problem] non-prescription drug in the sales, purchase cost advantages while providing a medicine, a payment system can avoid an increase in the load of the auxiliary excess unions. [Solution] a pharmaceutical sales system, information identifying a purchaser of drugs, medicines to be sold to purchasers of a received information, information identifying the purchaser to purchase some or all of the pharmaceutical according to aid auxiliary specifies payment, payment pharmaceutical sales assistant according to recognize conditions, be sold to purchasers of pharmaceuticals that payment to the seller if the auxiliary satisfies the condition, part or all of the payment for the purchase price of the pharmaceutical auxiliary charges generating billing information. [Drawing] Figure 1A