It is necessary for lens designer to calculate the estimated value of optical elements. In this case we made a trial of this calculation by use of the computer. This computer is called TOSBAC-3400 which have a main memory of sixteen thousand words and a disk memory of twenty four hundred thousand words. The program consist of fifty four sub programs which have about five thousand steps for all with FORTRAN base. It is possible to calculate the working hours for lens, prism and mirror.