A safety cover structure of a nuclear facility is disclosed. The safety cover structure includes: a cover portion rotatably installed on a body protection concrete slab to cover a cavity where a reactor pressure container is located; a driving portion configured to rotate the cover portion relative to the cavity; an opening and closing portion that is installed on the cover portion and is configured to allow materials resulting from cutting and dismantling of the reactor pressure container to move therethrough; a fire extinguishing portion configured to extinguish a fire generated inside the cover portion; a dose sensor installed in the cover portion and configured to measure a radiation dose emitted from the reactor pressure container; and an alarm portion configured to receive a sensing signal from the dose sensor and provide an alarm when the measured radiation dose exceeds a predetermined value.