PURPOSE: To measure the amount of respective colored yarns used for forming a pattern in a swivel patter using a multi-shuttle power loom.

CONSTITUTION: The amount of colored yarns used in a swivel pattern in a woven fabric having the swivel pattern by a multi-shuttle power loom is calculated as follows. The length of the colored yarns required for the swivel pattern itself and the length of slack yarns required for phenomena of 'hooking' (P) and 'pressing' between the colored yarns caused by a prescribed pattern on the back surface of the aforementioned woven fabric are obtained based on a textile design or computer graphic figure pattern data used for weaving the above-mentioned woven fabric, based on the running sequence and moving positions of shuttles or based on a medium such as floppy disc, optical disc, hard disc or IC card in which pattern card data used for weaving the aforementioned woven fabric are inputted. The sum total thereof is used to calculate the amount of the colored yarns (A) used for the aforementioned swivel pattern.