A power adapter includes a casing, a first connector, a rotary mechanism and a second connector. The first connector is rotatably disposed on a bottom of the casing. A first opening and a second opening are formed on the casing. The rotary mechanism is disposed between the casing and the first connector. The second connector is movably disposed inside the casing and connected to the rotary mechanism. The second connector is electrically connected to the first connector. An external plug inserts into the seconding opening to connect the second connector. The second connector is pushed by the external plug to drive the rotary mechanism to rotate the first connector, and a part of the first connector protrudes from an inner of the casing via the first opening.