In a lens actuator for use with an optical recording and reproducing apparatus in accordance with a plurality of different multiplied response numeric values to record or reproduce to or from an optical recording medium, the lens actuator actuates an objective lens to control focusing and tracking and includes a fixed magnetic circuit including a magnet as a magnetic flux generating source and a back yoke, a support structure that is elastically displaceable depending on a thrust generated amount; and a movable part including a holder fixing the objective lens and a solenoid coil capable of generating a focusing thrust and a tracking thrust in accordance with current values, respectively. And in the lens actuator, a resonance frequency around a tangential axis is set to be different from spindle rotation frequencies corresponding to the plurality of multiplied response numeric values.