According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, a sensor, a non-volatile semiconductor storage device, and a controller. The magnetic head performs writing and reading to and from the magnetic disk. The sensor detects a degree of a physical influence applied from an outside. The controller generates a log when a detection value detected by the sensor satisfies a condition for abnormality determination, and stores the log in the non-volatile semiconductor storage device in response to generation of the log.