PURPOSE: To give an excellent color grid print to a knitted woven base material by printing a color atlas on the same test base material as the woven base material to be printed under the same printing conditions as predetermined printing conditions.

CONSTITUTION: A printing original 1 having a design thereon is visually compared with a color atlas A of each of respective pixels. A color print of each pixel of the original 1 is visibly decided, and a color field F nearest a color impression is decided in the atlas A. Data regarding printing inks of three types at the maximum contained in the field F and regarding grid percentages are input to a control compute of a grid film exposure unit 5 by an input unit 55, and the pixel is formulated. The unit 5 manufactures grid films 58 for the individual inks based on the input grid percentages.