An in-vehicle apparatus includes: a flash memory; a memory controller for executing an initialization process; a backup power source; a power source; a controller; and a power source controller. According to incompletion of initialization, the controller executes standby/boot process. According to completion of initialization, the controller executes the boot process. According to reception of data backup instruction, the controller stores data in the memory. The power source controller switches to a trigger standby mode. According to trigger, the power source controller inputs the energization instruction to the power source. According to termination of trigger, the power source controller inputs the data backup instruction to the controller. According to completion of backup, the power source controller halts to input the energization instruction, and switches to the trigger standby mode. According to incompletion of backup, the power source controller resets the switch and the power source.