Purpose: This study investigates Korean speech sound development, including articulatory error patterns, among the Japanese-Korean children whose mothers are Japanese immigrants to Korea. Methods: The subjects were 28 Japanese-Korean children with normal development born to Japanese women immigrants who lived in Jeonbuk province, Korea. They were assessed through Computerized Speech Lab 4500. The control group consisted of 15 Korean children who lived in the same area. Results: The values of the voice onset time of consonants /$p^h$/, /t/, /$t^h$/, and/$k^*$/ among the children were prolonged. The children replaced the lenis sounds with aspirated or fortis sounds rather than replacing the fortis sounds with lenis or aspirated sounds, which are typical among Japanese immigrants. The children showed numerous articulatory errors for /c/ and /I/ sounds (similar to Koreans) rather than errors on /p/ sounds, which are more frequent among Japanese immigrants. The vowel formants of the children showed a significantly prolonged vowel /o/ as compared to that of Korean children ($P$<0.05). The Japanese immigrants and their children showed a similar substitution /n/ for /?/ [Japanese immigrants (62.5%) vs Japanese-Korean children (14.3%)], which is rarely seen among Koreans. Conclusion: The findings suggest that Korean speech sound development among Japanese-Korean children is influenced not only by the Korean language environment but also by their maternal language. Therefore, appropriate language education programs may be warranted not only or immigrant women but also for their children.