Disclosed herein are a microtubular honeycomb carbon material obtained by heat-treating cellulose fiber, a production method thereof, a microtubular reactor module fabricated using the microtubular honeycomb carbon, a method for producing the microtubular reactor module, and a microcatalytic reactor system comprising the microtubular reactor module. A carbon material having a new structure is produced by heat-treating cellulose fiber, and a catalytic reactor system having a new structure is constructed by coating the surface of the carbon material with a metal catalyst. Cellulose carbide, used as the reactor material, is very simple to produce. Because it has a micro honeycomb structure having a large number of microchannels and a large number of mesopores, it can be loaded with a large amount of a catalyst compared to the prior material having the same area, and thus it is useful as a catalyst support, and the reaction efficiency can be maximized. Also, the microcatalytic reactor system can be used in applications including very small steam reformer systems that use biomass fuel such as ethanol, fuel cell reactor systems, VOC and low-concentration-hydrogen treatment systems operable below 200 .quadrature., micro heat exchangers, and natural gas reformer systems. Thus, the invention is a useful, industrially applicable invention.