To prevent a cable band from becoming loose or coming off from a fastening lock.

In the method of automatically binding a long cable, a cable band 2 is delivered, is passed through a fastening lock 1, wound around a cable bundle, returned back to the inside of the lock, strained in the opposite direction by the reverse rotation of a driving motor, and is cut in the back of the lock. After the front end of the band goes through the through passage of the lock and wound around the cable to be bound, the end is introduced until the same hits a partition wall between the insertion passage and the thorough passage of the lock. The output of the driving motor which changes when the end hits the wall is determined as a signal value for the reverse rotation of the motor and/or the feed length of the band needed until the front end of the band hits the wall starting from a specific start position is determined as a control value or a signal value for the reverse rotation of the motor.