In a portable electronic apparatus, a cover device includes a stand unit provided on a cover body. The stand unit includes a support member connected to and pivotable relative to the cover body. A foldable limiting member is connected to the support member and is connected to the cover body for limiting the support member at the supporting position. The cover device is assembled removably on a user interface device for protecting an operating surface of the user interface device when the support member is in a collapsed position, where the support member lies on the cover body, and is removed from the user interface device to permit movement of the support member to a supporting position, where the support member forms an angle with the cover body for positioning the user interface device on the stand unit.