Provided is a 360-degree image data processing method performed by a 360-degree video reception apparatus. The method includes receiving 360-degree image data, obtaining information on an encoded picture and metadata from the 360-degree image data, decoding a picture based on the information on the encoded picture, rendering the decoded picture and an overlay based on the metadata, in which the metadata includes overlay related metadata, the overlay is rendered based on the overlay related metadata, the overlay related metadata includes information on an alpha plane of the overlay, and the information on the alpha plane of the overlay is included in a image item or a video track.