A door structure includes a cover for covering an accommodating space formed on a housing, a lodging part connected to an end of the cover for lodging in a slot on the housing, and a first inverse hook part connected to the housing and disposed adjacent to a hole on the housing. A first inclined surface is formed on a side of the first inverse hook part. The door structure further includes a second inverse hook part connected to a side of the cover. A second inclined surface is formed on a side of the second inverse hook part. The second inverse hook part is inserted into the hole on the housing so that the second inclined surface of the second inverse hook part wedges with the first inclined surface of the first inverse hook part.