In order to study on the spermatogenic function and the sexual maturity in male three-way crossbred ((Berkshire × Hampshire) × Landrace), this experiment was conducted to investigate the testicular development and the spermatogenic function by means of repeating biopsy testes at one month internals from one to 4 months of age and 15 days intervals from 4 to 6 months of age and the quality of semen collected after 27 weeks of age. 1. In the testicular development, the scrotum circumference increased steadily with increasing age up to 3 months of age, but increased rapidly after 4 months of age. The correlation between body weights, testicular lengths, testicular widths, and scrotum circumferences were statistically highly significant (p$lt;0.01). 2. The seminiferous tubules increased steadily at 3 months of age, increased apparently in diameter at 4 to 6 months of age. The percentage of intratubular tissue in the testis increased apparently at 4 to 6 months of age. 3. Only indifferent supporting cells, spermatogonia and spermatocytes were present in the seminiferous tubules at 3 months of age. Spermatids were appeared from 4 months of age, the percentage of which increased rapidly up to 5.5 months of age. 4. The first ejaculation of spermatozoa were observed in 1 of the 4 boars at 27 weeks of age, in 2 of the 4 boars at 29 weeks and in all of the 4 boars at 30 weeks. 5. The total volume ejaculated, sperm concentration and percentage of alive spermatozoa per ejaculate averaged 196.7㎖, 284.77x 10^6/㎖, and 80.0, respectively, at 35 weeks of age. On the basis of the above results it is concluded that three-way crossbred boars reached puberty at 27 seeks of age and can be used for breeding at about 35 weeks of age.