An inverter for an electric vehicle includes a speed instruction generating unit, a frequency voltage converting unit, an integrator and a 2-to-3 phase converter. The speed instruction generating unit outputs a speed instruction for changing the rotational frequency of an electric motor based on the on/off of a signal outputted from the accelerator pedal. The frequency voltage converting unit outputs a voltage instruction based on the frequency of the speed instruction. The integrator outputs a rotational angle by performing integration on the frequency of the speed instruction. The 2-to-3 phase converter receives the voltage instruction and the rotational angle and converts the received voltage instruction and rotational angle into three-phase voltage instructions.