A cutting apparatus is provided for cutting a sheet material. The cutting apparatus includes a bed for resting thereon the sheet material, a hollow rail structure spaced from the bed, a cutting element moved along the hollow rail structure to travel on the sheet material and cut it in a desired manner, a holding plate coupled to the hollow rail structure for depressing the sheet material on the bed to facilitate the cutting operation of the cutting element, and a sustaining element disposed in the hollow rail structure. The sustaining element sustains against an upper inner surface of the hollow rail structure to lift up the holding plate and sustains against a lower inner surface of the hollow rail structure to put down the holding plate.