When drugs are prepared according to drug preparation order sheets printed by drug preparation order printers, it is desired to freely set the relation with the printers by setting data without directly connected and fixed to a control program of a control unit of a drug preparation order system so as to cope with e.g. relocations of drug preparation tables. As the drug preparation instruction system, a control unit and a plurality of drug preparation order printers are provided. In the data storage portion of the control unit, data showing the relation between drugs and drug types are stored. By reading drug type codes from inputted drug data, and by reading printer numbers corresponding to the respective drug type codes from a printer setting portion in which are stored data showing the relation between drug type codes and printer numbers, drug data are printed individually by the printers of the set numbers.