A vector control apparatus configured to control tension of a motor, characterized by: said vector control apparatus being configured to perform said control free from computation of a diameter value of the motor by generating command velocity information using a compensation gain value substituting the diameter value of the motor; a tension velocity generator configured to generate the command velocity information for constantly maintaining a tension of the motor by adding an output of a PID (Proportional Integral Differential) controller to a multiplication of the compensation gain value and a command linear velocity inputted by a user; and a vector controller configured to perform a tension control of the motor by receiving the command velocity information provided by the tension velocity generator, wherein the tension velocity generator includes: a comparator configured to compare a PID command inputted by a user with a PID feedback value and to output an error of PID value in response to the comparison, the PID controller configured to output a PID output for compensating the error of the PID value outputted from the comparator, a compensation gain computing element configured to compute a compensation gain by determining the PID output, a multiplier configured to multiply a command velocity inputted by a user for control of the motor by the compensation gain, and an adder configured to add a command velocity outputted from the multiplier and a PID output outputted from the PID controller. said vector control apparatus being configured to perform said control free from computation of a diameter value of the motor by generating command velocity information using a compensation gain value substituting the diameter value of the motor; a tension velocity generator configured to generate the command velocity information for constantly maintaining a tension of the motor by adding an output of a PID (Proportional Integral Differential) controller to a multiplication of the compensation gain value and a command linear velocity inputted by a user; and a vector controller configured to perform a tension control of the motor by receiving the command velocity information provided by the tension velocity generator, wherein the tension velocity generator includes: a comparator configured to compare a PID command inputted by a user with a PID feedback value and to output an error of PID value in response to the comparison, the PID controller configured to output a PID output for compensating the error of the PID value outputted from the comparator, a compensation gain computing element configured to compute a compensation gain by determining the PID output, a multiplier configured to multiply a command velocity inputted by a user for control of the motor by the compensation gain, and an adder configured to add a command velocity outputted from the multiplier and a PID output outputted from the PID controller. a comparator configured to compare a PID command inputted by a user with a PID feedback value and to output an error of PID value in response to the comparison, the PID controller configured to output a PID output for compensating the error of the PID value outputted from the comparator, a compensation gain computing element configured to compute a compensation gain by determining the PID output, a multiplier configured to multiply a command velocity inputted by a user for control of the motor by the compensation gain, and an adder configured to add a command velocity outputted from the multiplier and a PID output outputted from the PID controller.