A method and apparatus for encoding and/or decoding depth image-based representation (DIBR) data are provided. The encoding method includes: converting 3-dimensional (3D) volume data into adjustable octree data with predetermined labels given to nodes; by referring to the labels, encoding nodes of the adjustable octree from the root node to leaf nodes by a modified breadth-first search (BFS) method allocating priorities among children nodes; and generating a bitstream with predetermined header information and encoded node data. The decoding method includes: extracting header information containing at least resolution information of an object, from a bitstream and decoding the header information; calculating the number of nodes by using the resolution information of the header, and by a modified BFS method allocating priorities among children nodes, decoding each node of a tree from the root node to leaf nodes; and restoring an adjustable tree by using decoded nodes. According to the method and apparatus, a huge amount of 3D volume data can be encoded with a high efficiency, and volume data with an arbitrary resolution as well as volume data with a fixed resolution can be encoded with a high efficiency. Accordingly, with a small amount of data, 3D volume data with a high picture quality can be restored. In addition, since a progressive bitstream is generated, 3D volume data can be shown progressively when decoding is performed.