This study analyses how Russian speakers produce Korean affricative acoustically and phonetically, in comparison with the sound production of Korean native speakers. Focusing on why Russian speakers made pronunciation errors in a particular way, we made an experimental comparison of two different kinds of Korean affricative produced by Russian speakers and Korean native speakers. For our experiment, the voice onset time of closure and fricative at the Word-initial position and pitch value of the following vowel were measured. The closer duration, the voice onset time of closure and fricative, and the pitch value of the following vowel were also measured and computed at the word-medial position. By contrasting the pronunciation of 10 Russian speakers with 10 Korean native speakers, we have drawn the following results: Of all the affricative that Russian speakers produced, the feature of aspiration /ㅊ/ was similar to that of Korean native speakers except that the voices onset time of the sound was extremely long in the word-initial position and the word-medial position. But on the other hand, when Russian speakers pronounced /ㅈ/, they tended to have short voices onset times and to pronounce it with a voiced sound. So it appears that the Russian speakers pronounce a lenis affricative /ㅈ/ like a fortis affricative /ㅉ/. When the Russian speakers pronounced /ㅉ/ in word-medial position, they showed a strong tendency to pronounce it as voiceless affricative We contend that these pronunciation errors by Russian speakers are caused by the different phonological system. That is, unlike Korean affricative system, there are only two distinctive consonants in Russian affricate system; thus, when Russian speakers pronounce a lenis affricative /ㅈ/, they perceive it as having [+constricted glottis] in a lenis affricative /ㅈ/.