A portable electronic device includes a main body, a door and a latch. The main body includes a positioning concave area on a bottom surface thereof. The positioning concave area has a cutout at a first edge, and an inclined surface and a guide edge at an opposite edge. The door is detachably connected with the bottom surface of the main body. The latch is slidably connected with a through hole of the door. The latch has an engaging portion and a guiding portion at two opposite ends. When the door is assembled to the bottom surface of the main body, the engaging portion inserts into the cutout. When the door is taken apart from the bottom surface, the engaging portion is removed from the cutout, and the guiding portion slides along the guide edge to move the door along a direction perpendicular to a long axis of the latch.