Abstract: A motor driving control apparatus comprises a current detecting section for detecting an output current from an inverter section; a current control section for outputting a voltage instruction to a PWM section from the detected current value, a current instruction from an external device, and from a positional signal of an encoder connected to a motor; and a PWM section for outputting a PWM signal to the inverter section according to a voltage instruction, and an encoder I/F section for receiving a positional signal for the encoder is provided in an external interface section, the current control section and PWM section are provided in an N potential control section connected to the external interface section, and the external interface section transmits the current instruction and the positional signal inputted into the encoder I/F section through serial communications via an insulating section.