Abstract: Disclosed is a technology for transmitting 3D contents composed of point clouds. According to an aspect of the present disclosure, provided is an apparatus for transmitting 3D contents, including: an input configured to receive a point cloud to be converted into a 2D image; a global grid generator configured to create a global grid that determines a size of a 2D image to be converted from the point cloud; a point cloud converter configured to create a V3C bitstream in which the point cloud is converted to a 2D image of a size determined by the global grid based on V-PCC; and a grid information extractor configured to extract size information of the global grid from the V3C bitstream; an encapsulator configured to create ISOBMFF data based on the V3C bitstream and the extracted global grid size information; and a transmitter configured to transmit the ISOBMFF data.