A motor control unit that driving-controls a motor by an inverter based on a current command value calculated with a steering torque from a torque sensor, and a motor release switch comprising field-effect transistors (FETs)is connected between said inverter and said motor, and comprises: a control section to detect states of sensors including said torque sensor and an assist state of said inverter, to turn-ON or turn-OFF a control of said inverter based on a detection result and to detect whether an abnormality is existed or not; a motor rotational speed detecting section to detect a motor rotational speed of said motor; an energy calculating section to select a motor back electromotive force voltage and regenerative currents by using a data table based on said motor rotational speed and to calculate an energy by using data thereof; a judging section to turn-OFF all of said FETs of said motor release switch when said energy is compared with an area of safety operation of said FETs and said energy is within said area of safety operation; and a state detecting section to detect whether an abnormality is existed or not based on information from an abnormality detecting section (131, 135) that detects an abnormality of said sensors and said inverter, wherein said control section turns-ON said control of said inverter when said state detecting section does not detect said abnormality and turns-OFF said control of said inverter when said state detecting section detects said abnormality, and wherein a temperature detecting section to detect a temperature of said FETs or a temperature around said FETs is provided, and said control section more accurately calculates said area of safety operation depending on said temperature by calculating said area of safety operation based on a temperature detection value that is detected at said temperature detecting section, characterized in that a timer is provided in said judging section, said timer is reset when said energy is out of said area of safety operation, and said timer is counted-up when said energy is within said area of safety operation, a time that said energy is within said area of safety operation is measured by said timer, and an FET-OFF signal is outputted when a state that said energy is within said area of safety operation continues for a predetermined time, and a current to calculate said energy is selected from said regenerative currents depending on an abnormality mode detected at said state detecting section. a control section to detect states of sensors including said torque sensor and an assist state of said inverter, to turn-ON or turn-OFF a control of said inverter based on a detection result and to detect whether an abnormality is existed or not; a motor rotational speed detecting section to detect a motor rotational speed of said motor; an energy calculating section to select a motor back electromotive force voltage and regenerative currents by using a data table based on said motor rotational speed and to calculate an energy by using data thereof; a judging section to turn-OFF all of said FETs of said motor release switch when said energy is compared with an area of safety operation of said FETs and said energy is within said area of safety operation; and a state detecting section to detect whether an abnormality is existed or not based on information from an abnormality detecting section (131, 135) that detects an abnormality of said sensors and said inverter, wherein said control section turns-ON said control of said inverter when said state detecting section does not detect said abnormality and turns-OFF said control of said inverter when said state detecting section detects said abnormality, and wherein a temperature detecting section to detect a temperature of said FETs or a temperature around said FETs is provided, and said control section more accurately calculates said area of safety operation depending on said temperature by calculating said area of safety operation based on a temperature detection value that is detected at said temperature detecting section, characterized in that a timer is provided in said judging section, said timer is reset when said energy is out of said area of safety operation, and said timer is counted-up when said energy is within said area of safety operation, a time that said energy is within said area of safety operation is measured by said timer, and an FET-OFF signal is outputted when a state that said energy is within said area of safety operation continues for a predetermined time, and a current to calculate said energy is selected from said regenerative currents depending on an abnormality mode detected at said state detecting section.