A vehicle-mounted apparatus includes: first and second voltage conversion circuits configured to convert voltages of electric powers supplied from first and second electric power supply circuits, to first and second predetermined voltages; first and second control circuits configured to be operated by the electric powers of the first and second predetermined voltages supplied from the first and second voltage conversion circuits, and to output first and second actuator command signals; first and second actuators configured to be actuated based on the first and second actuator command signals.