The apparatus is for controlling a torque of an electric rotating machine at a command torque by supplying command voltages in accordance with the command torque to a power conversion circuit driving the electrical rotating machine. The apparatus includes a detecting function of detecting an input voltage of the power conversion circuit to be power-converted and thereafter applied to the electric rotating machine as a drive voltage, and a control function of setting a command current corresponding to one of two current components in a 2-phase coordinate system of the electric rotating machine in accordance with a command torque directed from outside, and thereafter determining command voltages corresponding to two voltage components of the 2-phase coordinate system on the basis of the command current and the input voltage of the power conversion circuit.