To provide a corner block as a cushion material whose manufacturing cost can be reduced.

The corner block 10 is used in casing a product or a part for bringing the product or the part into contact with its corner to protect it. The corner block 10 comprises three blocks including first to third blocks 11, 12, 13 which are to come into contact with three planes of the corner. A fitting protrusion 11a to be fitted into a fitting recess 12a formed on a side end face of the second block 12 is formed on a side end face of the first block 11, while fitting protrusions 13a to be fitted into fitting holes 11b, 12b formed on side faces of the first and second blocks 11, 12 are formed at the center of two side faces orthogonal to each other of the third block 13.