1. A navigation apparatus comprising: a recording device configured to record a navigation program and user information on user, the navigation program recorded in the recording device including destination region information on destination region and version information on version; a reading device configured to read a navigation program stored in a portable storage medium, the navigation program stored in the portable storage medium including destination region information on destination region and version information on version; and a control circuit configured to execute a navigation function by reading and executing the navigation program recorded in the recording device, and to execute a program recording process and a backing up process, the program recording process and the backing up process being allowed to be performed in parallel, the program recording process reading the navigation program in the portable storage medium via the reading device and recording the read navigation program in the recording device, the backing up process backing up the user information recorded in the recording device, the control circuit further comprising: a destination region comparison section configured to execute a destination region comparison to compare the destination region of the navigation program stored in the portable storage medium with the destination region of the navigation program recorded in the recording device, wherein, when the destination region of the navigation program stored in the portable storage medium is different from the destination region of the navigation program recorded in the recording device, the program recording process is executed while executing a user information easing process to erase the user information currently recorded in the recording device without executing the backing up process, a version comparison section configured to execute a version comparison to compare the version of the navigation program stored in the portable storage medium with the version of the navigation program recorded in the recording device when the destination region of the navigation program stored in the portable storage medium is identical to the destination region of the navigation program recorded in the recording device, wherein, when the version of the navigation program stored in the portable storage medium is newer than the version of the navigation program recorded in the recording device, the program recording process is executed while the backing up process is executed.