PURPOSE: To enable to adjust easily a deflection from a target preset value of a braiding angle by detecting the deflection in an early stage, by displaying the braiding angle by calculating the same through the outside diameter of a long-sized material, the number of revolutions and a line speed of a bobbin.

CONSTITUTION: A long-sized material 10 is braided with a braiding material 11 by a first braiding machine 13 and the number of revolutions of a supply bobbin 13a at the circumference of the long-sized material is calculated by a measuring apparatus 14. Then the outside diameter of the long-sized material after braiding is measured continuously by a measuring apparatus 12. A second layer braided by a braiding machine 16 further while the number of revolutions of a bobbin 16a is being measured by a measuring apparatus 17 of the number of revolutions and the outside diameter is measured again by a measuring apparatus 15. Then the braided long-sized material is taken up by a take-up machine 18 and its line speed is detected by a measuring apparatus 19. These data are supplied to an arithmetic unit 20, tan-1(πdR/V) is calculated by CPU, and converted into an angle θ by a conversion table 21, so that braiding angles of the first and second braiding machines 13, 16 are displayed respectively moment by moment. Then the braiding angle is adjusted to a predetermined value in a short period of time by controlling the line speed.