The purposes of this study were to investigate the development of intelligence abilities between the hearing-impaired and the children of normal hearing. The subjects were sampled by 72 hearing impaired in day school and residential school for the deaf, and 72 normal children in primary public school. C.A. of the subjects was ranged from 10 to 12 years, conclusions obtained from the results of the Wechsler Intelligence Scale for Children Performance Test are as follows. 1) Total scores of intelligence test were not shown by significant difference statistically between the normal group and the hearing-impaired group. But was shown by 5% significant difference in 12 years old. 2) The scores of the sub-test of the normal group were higher than the hearing-impaired in 「picture arrangement」, 「digit symbol」, there was shown by 5% significant difference statistically for 「picture arrangement」 for the children aged 10-11 years but was lower in 「object assembly」. 3) There were not shown significant difference statistically between degree of hearing losses and intelligence.