1. A positioning servo controller comprising: a position controlling section which amplifies a position deviation between a position command issued from a higher-level unit and a position of a controlled object by a position loop gain, and which outputs the amplified deviation; a speed feedforward controlling section which sets a value that is obtained by adding a first feedforward compensation amount to the value output from said position controlling section, as a speed command, the first feedforward compensation amount being obtained by amplifying a differential value of the position command by a first feedforward gain; a speed controlling section which amplifies a speed deviation between the speed command and a speed of said controlled object by a speed loop gain, and which outputs the amplified deviation; an acceleration feedforward controlling section which sets a value that is obtained by adding a second feedforward compensation amount to the value output from said speed controlling section, as an acceleration command, the second feedforward compensation amount being obtained by amplifying a differential value of the first feedforward compensation amount by a second feedforward gain; an acceleration controlling section which amplifies an acceleration deviation between the acceleration command and an acceleration of said controlled object by an acceleration loop gain, and which outputs the amplified deviation as a torque command; and a torque amplifier which drives said controlled object on the basis of the torque command.