In a stabilizer control apparatus for transmitting a power through a speed reducing mechanism, a rolling motion of a vehicle body is restrained smoothly and rapidly, without being affected by transmitting efficiency of the speed reducing mechanism. As for a stabilizer (SBf) including a pair of stabilizer bars (SBfr, SBfl) disposed between a right wheel and a left wheel, and a stabilizer actuator (FT) driven by an electric motor disposed between them, the electric motor M is controlled in response to a turning state of a vehicle, to control a torsional rigidity of the stabilizer. Furthermore, the apparatus comprises relative position detection means for detecting the relative position of the pair of stabilizer bars (for example, obtained from a relationship between a rotational angle of the electric motor and a reducing speed ratio), and it is so constituted that the electric motor is controlled in response to the detected result.