Patent ID: 7363136

Claim:
A controller of an electric power steering apparatus, comprising: a steering assist control mechanism comprising an electric motor giving a steering assist force to a steering system; abnormality detection means for detecting an abnormality of the steering assist control mechanism; and abnormality data storage means for storing abnormality analysis data for analyzing the abnormality in the storage means when the abnormality of the steering assist control mechanism is detected by the abnormality detection means, wherein said storage means comprises an overwrite prohibition storage area for prohibiting an overwrite of said abnormality analysis data and an overwrite allowable storage area for overwriting and storing said abnormality analysis data, and wherein said abnormality data storage means is constituted to store an abnormality of the steering assist control mechanism detected by the abnormality detection means in said overwrite prohibition storage area when the abnormality is a first abnormality analysis data, and store the abnormality in said overwrite allowable storage area when the abnormality is the abnormality analysis data subsequent to the second time.