A slidable and automatic rotatable apparatus disposed in a portable electronic device and providing the portable electronic device, which includes a first housing and a second housing, with a first status and a second status is provided. The apparatus includes a third housing, a protruding part disposed on the second housing and opposite to the first track, and a rotary module passing through the second track. The third housing, which is fixed on the first housing and movably connected with the second housing, includes a first track, a second track, and a first rib disposed on a first side of the second track. A first end of the rotary module is fixed on the second housing, while a second end is disposed between the first housing and the third housing. The rotary module has at least one protruding point positioned at the second end for contacting the first rib.