PURPOSE: To quickly and accurately search the specific characters on a designing drawing without performing any window processing by extracting only the character data out of a CAD data, storing this extracted data in a character store file, and then checking whether the selected characters are included in the character store file or not.

CONSTITUTION: A computer aided design CAD system consists of a CPU 1, a magnetic disk 2, a computer CPU memory 3, a display data production part 4, a screen display part 5, a keyboard 6, and a character store file 8. Then all characters written on a drawing are stored in the file 8, and such a sequency is applied to check the number of characters that are selected by a light pen, etc., and stored in the file 8. Thus it is possible to quickly and accurately search the specific characters on a designing drawing without performing any window processing.