A linear actuator, comprising: a rotor; a lead screw coupled to the rotor; a stator is disposed inside of the rotor;and a nut part is screw-coupled to the lead screw and comprising a magnet; a boundary line between an first pole and an second pole of the magnet is located at a widthwise-directional center of the nut part, characterized in that a sensor unit configured to sense a change amount of magnetic flux depending on a position of the magnet and convert the sensed change amount of magnetic flux into a measured voltage data; a data unit configured to store a reference voltage data at the corresponding position of the magnet in the form of a table in advance; a judging unit configured to compare the reference voltage data with the measured voltage data at the corresponding position of the magnet; a position compensating unit configured to control the movement of the a nut part until the error between the measured voltage data and the reference voltage data is compensated to a value within a specific reference value range in the judging unit, an initialization driving unit configured to control the movement of the a nut part to align positions of the nut part and the sensor unit with respect to a linear movement direction of the nut part, wherein the initialization driving unit controls the movement of the nut part to allow a boundary line between the first pole and the second pole to be located at a center of the sensor unit with respect to the linear movement direction of the nut part, wherein, if the sensor unit senses the first pole when the nut part is moved forward, the initialization driving unit performs a first motion in which a forward movement of the nut part is stopped and a backward movement of the nut part is carried out, and if the sensor unit senses the second pole after the first motion, the initialization driving unit performs a second motion in which the movement of the nut part is stopped and a forward movement of the nut part is carried out, wherein the initialization driving unit repeatedly performs the first motion and the second motion a reference number of times. a rotor; a lead screw coupled to the rotor; a stator is disposed inside of the rotor;and a nut part is screw-coupled to the lead screw and comprising a magnet; a boundary line between an first pole and an second pole of the magnet is located at a widthwise-directional center of the nut part, characterized in that a sensor unit configured to sense a change amount of magnetic flux depending on a position of the magnet and convert the sensed change amount of magnetic flux into a measured voltage data; a data unit configured to store a reference voltage data at the corresponding position of the magnet in the form of a table in advance; a judging unit configured to compare the reference voltage data with the measured voltage data at the corresponding position of the magnet; a position compensating unit configured to control the movement of the a nut part until the error between the measured voltage data and the reference voltage data is compensated to a value within a specific reference value range in the judging unit, an initialization driving unit configured to control the movement of the a nut part to align positions of the nut part and the sensor unit with respect to a linear movement direction of the nut part, wherein the initialization driving unit controls the movement of the nut part to allow a boundary line between the first pole and the second pole to be located at a center of the sensor unit with respect to the linear movement direction of the nut part, wherein, if the sensor unit senses the first pole when the nut part is moved forward, the initialization driving unit performs a first motion in which a forward movement of the nut part is stopped and a backward movement of the nut part is carried out, and if the sensor unit senses the second pole after the first motion, the initialization driving unit performs a second motion in which the movement of the nut part is stopped and a forward movement of the nut part is carried out, wherein the initialization driving unit repeatedly performs the first motion and the second motion a reference number of times.