A vapor grown fine carbon fiber, each fiber filament of the carbon fiber comprising, in its interior, a hollow space extending along the fiber filament, and having a multi-layer structure, an outer diameter of 2 to 500 nm, and an aspect ratio of 1 to 100, wherein the fiber filament comprises a cut portion on its surface along the hollow space, a production method therefor, and electrically conductive material, a secondary battery and a gas occlusion material using the carbon fiber. The fine carbon fiber of the present invention is excellent in properties such as occlusion of gases such as hydrogen and methane, smoothness, electrical conductivity and thermal conductivity, and also excellent in dispersability, wettability and adhesion with a matrix such as resin.