A mobile ultrasonic diagnostic device comprising: a battery an adapter connection detection unit that detects the connection status of an AC adapter that supplies power to each constituent element of the device and a processing determination unit (determination unit) that determines the processing for each constituent element on the basis of the connection status of the AC adapter. Each constituent element (a processing unit and constituent elements other than the processing unit) are processed on the basis of the processing determined by the processing determination unit (determination unit), and, as a result, the device can be safely used even if there is a possibility that power cannot be supplied from the battery.