A mobile radio communication apparatus includes a first housing, a second housing foldable over the first housing, and a hinge part that foldably connects the second housing to the first housing around a rotational center axis, wherein the hinge part includes a one touch opening part that automatically opens the second housing from a folded state by a first angle relative to the first housing around the rotational center axis in a non-stop motion, an auxiliary rotational part that rotates the second housing around an orthogonal shaft orthogonal to the rotational center axis of the hinge part, and an opening permission section that allows the second housing to open at an angle greater than the first angle relative to the first housing.