This paper is a trial one on genetical analysis of lamellar flake industry. The writer is interested in role of the technique in each individual culture and its distributional relations. Materials available for present analysis were very few and incomplete, i. e. a museum collection in Engaru which was found while cultivation of the area and consisted of relatively comprehensive artifacts representing a prehistoric indu-stry, and specimens kept at other museum or private collections, most of which were separate finds found on the surface of the ground. In Engaru few potsherds and polished tools are found ; most of artifacts are flakes and chipped tooles such as arrowheads, spearheads, knives, scrapers etc., all of which are made of obsidian possibly brouht from adjacent river bed of the Yubetsu. Polyhedral cores are also found, and core scrapers (transformed polyhedral cores) are relatively dominant. Lamellar flakes are abundant. They were possibly produced by a systematic technique, from polyhedral cores. They have a considerably definite type as a whole differing from accidental ones. Other broader or angular flakes have also some common characteristics in platform-scar angles and dorsal ridges etc. A tendency is suggested that suitable flakes were selected to be trimmed intp tools ; lamellar flakes are utilized to produce knives, arrowheads and spearheads etc, while broader or angular ones for scrapers, borers etc. Lamellar technique might be a profitable method to meet active demands for various blades by hunters ; it might supply speedy and economicaly flakes of a type suitable for production of wanted tools, and spare their trouble to select and trim flakes for making of tools. As a whole, chipped to, except scrapers and some others, are slender. Chipping technique is generally fine ; chipped scars are shallow, long and more parallel. Such fine trimming may have genetical relation with lamellar technique. Three elements, (a) polyhedral cores, (b) lamellar flakes and (c) finely chipped slender blades seem to be closely related, in other words, there seems to be a functional relations between the flaking technique and the type of tools.In Hokkaido, the technique is closely connected with obsidian. Element (a), a direct evdence of the technique carried out in given place, is found at least from six localities ; 3 along or near River Yubetsu, 2 along River Tokachi (those rivers are main homes of obsidian in Hokkaido), and 1 in Kushiro City. Element (c) is more generally distributed, but in areas where obsidian might not be available for use freely, this element appears often as tools made of other amorphous rocks.All these elements appear to be found in subarctic zone from N. Asia to N.America, and connected with homogeneous local rocks such as obsidian, flint, agate, chalcedony etc. which are fit for chipped tools and of consideaably limitted occurence. While they are absent in circum pacific zone, i. e Japan proper, Korea, southern Manchuria, China proper and Indochina, etc. Moreover even in subarctic zone, distribution of those elements may possibly show lateral change such as local variation or lacal absence. And yet, on the other hand, those elements seem to be related to one another genetically.Such elements, or flaking technique and type of tools probably relatiug to Mesolithic tradition, may be some cultural traits indicating historical connections, there are however, further interesting problems ; how were distributions of those elements, or interrelations of them in each individual culture, or influence of environmental and sociocultural potentiality upon them?