Remarkable damage was caused by a thunderstorm with hail in a south part of Fukuoka prefecture on 28th May 1967. The damage was observed over a zonal district extending from Tosu (Saga prefecture) toKuroki, through Kurume, Jyoyo. Especially, the damage to agricultural products was heavy. The author has investigated this hail damage form the following points:1. Hail damages in the past.The largest hailstorms recorded in the Fukuoka prefecture was seen on Feb. 19, 1684, in Kurume. The maximum size of the stones was about 7cm in diameter, weighing aobut 82 grams. The author made use of a 285-year period (1682-1967), for a total 31 haildamage days, to investigate the relation between hail storms and the months. Haildamage occurred preimarily in May (31%), and secondarily in April (21%).2. Synoptic weather condition of hailfall.Various ways have been employed for collecting data from radar observations, aerial observation by pilots through flights over the area of the hail path, Weather Bureau's upper soundings, surface observations by the persons in the storm area and the author took photographs of hail damage area. Also the data for crop loss of hail storm were supplied by the public offices.A 5.7cm radar set operated at the Seburi radar site can depict thunderstorm cells in the storm by PPI photographs, . This photograph as indicated in Fig 4, helps delineate the hail path, its movement, development, and orientation. It also delieates the hail boundary within a 100km radar range. The echo areas shown reveal that the thunderstorm under study developed as a clam shell shape, the first hail falling from the south western edge of east-southeastward moving thunder storm cell (see echo area Fig. 6).From analysis of upper (850-, 700-, 500-, and 300mb levels) and surface synoptic maps of May 28, 1967, it is evident that the thunderstorm and hailstorm developed along a meso low pressure, pushing forward across south central mountains of Fukuoka (Minou mountains). The 500-mb level jet stream appeared to be about 27m/s, probably responsible for the development of the storm through its vertical shear effects on the vertical movements of the individual storm cells along the meso low.3. Distribution of hail damage.The topographic effect on hail distribution is of importance, because it determines the speed and direction of local winds and, in turn, affects the distribution of hailstorms.The author has made investigation on the duration and the begining and ending hours of storms, as well as the degrees of the haildamage. Data included the time of hailing (begining), size distribution of hailstones from photograph, stone density on the ground, lightning, direction of destructive wind, and estimates of crop and property damage damage types. The analysed haildamage lines are showr in Fig-6.4. Condition of hail damage.Damage caused by the hailstorm is vast. For small animals, the damage is serious when the hailstones range from 3 to 6cm in diameter. Stones of about 3cm diameter are considered disastrous to crops in general.Theoretically, the degree of damage inflicted upon plants by hailstorms depends upon the stone size, areal density, depth of coverage, duration of the storm, falling velocity, area coverage, and age of the plants. Heavy rainfall and severe wind accompanying the hail cause considerable addintional damage.It has been found that the area of crop damage coincides fairly closely with the density of stones; in general, the damged crop area coincides with the areas of stone density of 100 or more per square meter. Factors other than stone density influencing crop damage were a maximum stone size above 3cm diameter a longer point duration than 10 minutes, and a surface wind exceeding 20m/s. Finally, in the isohyetal analysis, it was revealed that the rain core was generally associated with the hailstorm and with 10mm rainfall during the 3-hour period