Provided is a light-scanning device may be designed to have a high resonance frequency and a large scanning angle. A mirror unit vibrates by using an arbitrary straight line as a rotation axis. A pair of first beam portions are disposed on a straight line that is parallel to the rotation axis, and support the mirror unit. A pair of second beam portions are disposed so as to be line-symmetrical to the pair of the first beam portions about the rotation axis as an axis of symmetry, and support the mirror unit. A pair of first arm portions respectively support the pair of first beam portions. A pair of second arm portions respectively support the pair of second beam portions. A pair of third beam portions support the mirror unit between the first beam portions and the second beam portions.