This application provides an inverter apparatus used in a motor controller, a motor controller, and a vehicle. The inverter apparatus includes a capacitor module, a power module, and a first heat sink. The power module includes a plurality of power transistors, and the plurality of power transistors are arranged in a flat manner in a direction perpendicular to a direction in which the power module and the first heat sink are stacked. The first heat sink is configured to dissipate heat for the power transistors in the power module, so that the power transistors operate in a proper temperature environment. The inverter apparatus provided in this application has a compact structure layout and high integration. This is conducive to implementing a miniaturization embodiment of the motor controller, and reducing difficulty of disassembling and assembling internal parts of the motor controller and costs.