Submillimeter wave CI line observations with Mount Fuji submillimeter-wave telescope by Dr. Hiroyuki Maezawa (Nobeyama Observatory)   We have constructed a 1.2 m submillimeter-wave telescope at the summit of Mount Fuji (3724 m) in July 1998. This telescope has been used in the large-scale mapping of the fine-structure lines of the neutral carbon atom (CI). For this purpose we developed a triple-band receiver , in which niobium-based SIS mixers were installed for the 345, 500, 810 GHz bands. CI is thought to exist mainly in a relatively diffuse part of molecular clouds, called a photodissociation region(PDR). CI would also exist even in the interior of a newly formed molecular cloud, since the conversion timescale of CI to CO is of the order of the dynamical time scale of the core (-10^6 yr) according to chemical model calculations. With the newly developed telescope we have carried out mapping observations of the CI 3P1-3P0 (492 GHz) line toward Heiles' cloud 2 region (HCL2) in Taurus dark cloud which is free from the influences of nearby OB stars and supernova remnants. In this talk CI-rich cloud found in the south part of HCL2 region is briefly described in relation to the formation processes of molecular cloud. The recent mapping observation of CI 3P2-3P1 (809 GHz) line toward the Orion Kleinmann-Low region which contains a typical PDR with a massive star forming region will also be mentioned.