A media processing device does not execute a media transportation process if the height of media stacked in a media storage unit is at an over capacity level, and reliably prevents problems such as damage to the media transportation mechanism caused by collision with the stacked media. If in the media processing device 200 the height of media stacked in a media storage unit 121, 122 is at a full stack level or over capacity level (step S33 returns yes or step S35 returns yes), an appropriate warning is output (step S34 or step S36) and collision accidents of the media transportation mechanism 131 can be prevented.