Provided is a motor position detecting unit that includes a first computing element configured to output three-phase back-electromotive foreces (back-EMFs) based on a linear computation; a second computing element configured to output three-phase back-EMF based on a non-linear computation; and a computing controller configured to receive a control signal, three-phase voltage and current, and selecting any one of the first and second computing elements based on the received control signal, the received three-phase voltages and currents, wherein the control signal includes information on operation modes of an external motor.