Disclosed is a carbon fibrous structure which comprises a granular part and 2-20 pieces of carbon fibers each of which has an outside diameter of 15-100 nm and which are extend outwardly from the granular part, wherein the granular part is produced in a growth process of the carbon fibers, wherein the size of granular part is 1.3 or more of times larger than the outside diameter of the carbon fibers, and wherein the mean length of the carbon fibers is not more than 20 μm. The carbon fibrous structure improves the physical properties of the matrix, such as electric, mechanical, or thermal properties, while maintaining the other properties of the matrix, even when added at a small amount.