An AC adaptor has an AC plug having wider contact portions facilitating better contact despite the displacement. AC plug 3 of AC adaptor 3 has a pair of conductive blades 4, an end surface with the blades projecting with a substantially right angle, a first surface and a first rotary shaft on a first side surface. On a second side surface opposite to the first side surface, there are provided a second surface and a second rotary shaft. A first and second planar contact portions which are electrically connected respectively to a first and second conductive blades are configured respectively to project slightly from the surfaces of the first and second rotary shafts. On a circuit board in the case, there are provided conductive spring terminals 17 with projecting portions thereof making resilient contact with the first and second planar contact portions 15.