Unlike Seoul dialect, in the Busan dialect, /ㅅ/ and /ㅆ/ are phonemically non-distinctive and realization of tensing is non-productive, on the other hand, that of voicing is productive. In order to discover causes of such characteristics in Busan dialect, this paper firstly compared acoustic characteristics of Seoul dialect with those of Busan dialect on fricative /ㅅ/ and /ㅆ/. The result showed that Busan dialect has much shorter length of friction and aspiration intervals of word initial and word-medial position than Seoul dialect. I expect that these results are important keys to discover causes of the following characteristics of Busan-dialect - non-distinction, non-productivity of tensing, and productivity of voicing - on Fricative /ㅅ/ and /ㅆ/.