The present invention discloses an USB/OTG-interface storage card, wherein the USB/OTG interface unit is planarized such that the volume thereof can be reduced obviously and the USB/OTG-interface storage card can be more lightweight, slim. Further, the planarized interface unit enables the USB/OTG-interface storage card to be inserted completely inside a slot of an electronic device, and therefore, the user will no more scruple the bumps induced by the conventional USB/OTG-interface storage device's projecting from the electronic device.