An electronic device including an external-memory-medium installing portion in which an external memory medium storing contents data, a display portion for displaying the contents data, a sound generating portion for generating a sound, a power-shut-down-requirement receiving portion for receiving a requirement for shutting-down a power supply to the electronic device, a monitoring portion for determining whether the external memory medium is installed in the external-memory-medium installing portion, a sound-generation commanding portion for commanding command the sound generating portion to generate an alarming sound when the monitoring portion has determined that the external memory medium is not installed in the external-memory-medium installing portion while the contents data are displayed, and a power supply control portion for inhibiting an operation to shut down the power supply to the electronic device when the power-shut-down-requirement receiving portion has received the requirement for shutting down the power supply while the contents data are displayed.