A rotary device includes a rotary shaft, a rotary body that is supported by the rotary shaft, and rotates about the rotary shaft, and at least one plate-like member having a central point that serves as a center of rotation when the plate-like member rotates, the plate-like member having an outer peripheral portion, the plate-like member including at least one cutout formed by cutting out the outer peripheral portion of the plate-like member at positions that are symmetric with respect to a straight line passing through the central point, the plate-like member being secured to the rotary shaft to rotate together with the rotary body as the rotary shaft rotates.