A 360 image data processing method performed by a 360 video receiving device, according to the present invention, comprises the steps of: receiving 360 image data; acquiring information and metadata on an encoded picture from the 360 image data; decoding the picture on the basis of the information on the encoded picture; and rendering the decoded picture and an overlay on the basis of the metadata, wherein the metadata includes overlay-related metadata, the overlay is rendered on the basis of the overlay-related metadata, and the overlay-related metadata includes information on a region of the overlay.