A hinge structure, for rotatably supporting a mirror surface of a micromirror device which rotates the mirror surface around at least an axis for scanning a beam, includes a linear body with one end joined to a surface which is rotated around the axis and the other end joined to a surface which does not rotate around the axis. The linear body includes a linear central part situated on the axis and a pair of extension parts extending from both ends of the central part to both ends of the linear body respectively to surround the central part in the same direction. The extension parts are formed so that space between them will be substantially constant. By the above composition, the hinge structure delivers high spring performance while being small-sized.