It has been found by Cavallito (1944) that garlic (Allium sativum L.) has a strong antibacterial activity and the active principle of garlic is named "Allicin" and it has been confirmed by Stoll et al. (1948) that the allicin is derived from the alliin-alliinase system. Nevertheless, one worker in Japan (1951) stands on another view point which the effective component of garlic is some sugar-proteim because he could not find alliin in the native garlic. We intend to make sure that the alliin is contained in the native garlic, by using Hitachi Amino acid Analyser with Fraction Collecter and compared with garlic of other countrys' production. As the result of examinations, we found that the good amounts of alliin is contained in the native garlic also. The contents of alliin in garlic is varied by the species, the cultivation mode, and the district of production. The form of alliin in the tissue is a free style, and thereupon it is easy to change its chemical conformation by the method of extraction. We compared the relative capacity between 1 allicin unit by Klein (1954) and 1 cup unit by Schmidt et al. (1947). Furthermore we tested the antibiotic spectrum, using the pure crystallized alliin with the sufficient amount of raw alliinase gained by the isoelectric point precipitation and checked upon wide spectrum for Mycobacterium tuberculosis, Gram-positive and negative bacteria, and some fungi.