are connected to addition terminals u and subtraction terminals d of the counters 32c 33c minus terminals m m indicating that contents of the counter 32c 33c is zero or negative are feedback connected to the and gates 32b 33b through the inverters 32d 33d and the terminal m of the counter 32c and the minus terminal n of the counter 33c are cross connected to the and gates 33a 33b and the and gates 32a 32b respectively outputs of the counters 32c 33c are in the form of a pressure correction signal sp and an angle correction signal sa respectively with respect to the pressure controller 10 and the timing controller 20 when the contents of counter 32c 33c is zero or negative output u03b4p u03b4 u03b8 of the counter is stopped the control operation carried out by the aforementioned control device will be described hereinafter it is now assumed that the pressure correction signal sp and the angle correction signal sa from the condition setting section 30 are not present their values being zero picking is started for the weft yarn w at the set start angle u03b8o set to the start angle setter 21 of the timing controller 20 and the weft yarn w arrives at the anti picking side at the set arrival angle u03b8eo set to the.