The present invention provides a portable telephone comprising an openable/closable casing having a display 13a, a magnetic sensor 18b for detecting whether the casing is opened or closed, and a control circuit 10. When a message is received with the casing closed, the control circuit 10 displays the contents of the received message on the display 13a. When the casing in an opening state is thereafter detected, the control circuit 10 displays on the display 13a a reply-message-preparation screen for preparing a reply message to be sent to a sender of the received message.