The place of articulation of the Korean plain affricate /c/ and the obstruents /t, s/ is articulatorily and acoustically examined in the intervocalic positions /a―a, a―i, a―u/ taken from four subjects in three dialects. The articulatory data of direct palatograms and linguograms have shown that in these contexts, the plain affricate is not post-alveolar as usually assumed in the literature, but alveolar, just like the alveolar consonants /t, s/, despite some speaker variation regarding the active articulator (tip, blade, anterodorsum). The examination of LPC data has also shown that the affricate is alveolar, like the consonants /t, s/, both for its stop part and for its frication part. The phonetic results are then confirmed by the review of Skalicková's (1960) palatogram of the affricate, and the comparison of X-ray data of the affricate /c/ to those of the Korean obstruents /t, s/ (Skalicková 1960), the Korean vowel /i/ (Han 1978) and post-alveolars in other langauges such as Czech (Danes et al. 1954) and Polish (Wierzchowska 1980). Based on the present phonetic results, we propose that, following IPA usage, the Korean plain affricate is transcribed as /ts/.