It has been reported by forgoing investigators that level of intelligence is generally lower than in rural school chidren. Our problem was to ascertain the level of intellectual development of the children and preadolescents in the schools of isolated villages, where the life condition is more disadvantageous than that of average rural villages. Subjects and Procedure: Since the verbal test is more difficult than the non-verbal one for rural school children who are placed in an unfavorable condition for janguage development, we made use of two kinds of intelligence test, Tanaka Intelligence Test A(verbal)and Tanaka Intelligence Test B(non-verbal). Our subjects were primary school children, ranged in age from 9 to 11 years, and pupils of junior high schools, ranged in age from 12 to 15. For the purpose of comparison, the same examination was given to pupils of Sendai City. The number of subjects was 1082 in the rural group and 369 in the city group. Results: (1)The average scores obtained for Test B in four villages were invariably about 45(SD≒9)of T-score and this is significantly lower than that of the city grop(T-score was about 51). Differences of the average between villages are rather small and we find no significant difference between farm villages and fishing villages. (2)The average score of Test A was significantly lower than that of Test B. (3)An analysis of 14 sub-tests contained in both tests shows that the score of the rurel subjects is lower than that of the city group for almost any of the sub-tests. But it seems that some of fhem(number series, reasoning etc.)are especially difficult for rural subjects and others(maze, substitution etc.)are not.