The present invention relates to a process for producing a fine diamond characterized by that an explosive composition containing a compound having an aliphatic hydrocarbon ring with 4 to 15 carbons, a fullerenes or a tubular or fiber carbon nanostructure having a diameter of 1 to 100 nm as a carbon raw material is exploded for explosive synthesis, and a fine diamond obtained by said process; the ultrafine particulate diamond of 1 to 3 nm is expected, as a single nano diamond, for application of the fields such as ultrafine processing, the uniform, spherical fine particulate diamond of 0.01 to 100 μm is expected as abrasive grains for polishing in precise processing and the like, and the needle diamond is expected for application in various sensors and the like.