An in-vehicle control apparatus includes: a first inverter; a second inverter; and a voltage conversion part configured to increase or decrease an operation voltage of one of the first inverter and the second inverter by an open-close control of a switch and supply the increased or decreased operation voltage as an operation voltage of another of the first inverter and the second inverter. The voltage conversion part includes: a reference voltage line; a low-voltage-side switch that is connected to and between the reference voltage line and a high-voltage-side power line of the second inverter; and a high-voltage-side switch that is connected to and between a high-voltage-side power line of the first inverter and a high-voltage-side power line of the second inverter. The in-vehicle control apparatus includes: a detection part that detects a short circuit failure of the low-voltage-side switch; and a control part that performs a phase short circuit control that short-circuits at least one of a plurality of low-voltage-side switches and a plurality of high-voltage-side switches of the second inverter upon detection of a short circuit failure of the low-voltage-side switch by the detection part.