A mobile device is equipped with a transmitting function to transmit data. When a power switch is turned off during data transmission, a transition is made to a transmission-during-power-off mode that continues data transmission. The transition to the transmission-during-power-off mode is performed when an inquiry is made on a screen as to whether transmission will be performed and “continue” is subsequently selected. In this mode, even when the mobile device with the power switch being turned off is carried around, data transmission is continued and data is recorded into a storage section of a home personal computer.