Abstract: An auxiliary device for mobile electronic apparatus includes an electrically insulative housing for accommodation a mobile electronic apparatus, an electrical connector slidably coupled to the electrically insulative housing and movable between an extended position to electrically connect a card-edge connector thereof to the accommodated mobile electronic apparatus in the electrically insulative housing and a received position to electrically disconnect the card-edge connector from the accommodated mobile electronic apparatus, and a back cover detachably mounted in a back side of the electrically insulative housing to electrically connect a storage battery cell to the electrical connector for charging the accommodated mobile electronic apparatus in the electrically insulative housing.