[Problem]
An object of the present invention is to provide a power state diagnosis method and a power state diagnosis apparatus that do not need to make a control period fast and also do not need to excessively increase a responsibility, and do not give an uncomfortable feeling to a driver.
[Means for Solving the Problem]
The present invention is a power state diagnosis method that diagnoses a power state of a vehicle which comprises an electrical control system supplied from a power supply and a motor controlled by a vector control method, comprising: starting a diagnosis of said power state at a time that an ignition key is switched from “OFF” to “ON” or at a time that said ignition key is switched from “ON” to “OFF”, storing a value obtained by adding an offset to an angle of said motor that is read at a start of said diagnosis as a pseudo-motor-angle, performing said vector control based on said pseudo-motor-angle during said diagnosis, and diagnosing said power state based on a voltage that is supplied to said motor.