In a series of three experiments, native speakers of Japanese performed serial ordered written recall of visually presented Japanese kanji characters that varied systematically in visual and phonological similarity. Overall effects of phonological similarity were observed for retention of serial order under silent reading in Experiments 1 and 3 and they disappeared in articulatory suppression conditions in Experiments 2 and 3. All three experiments showed main effects of visual similarity even in articulatory suppression conditions in Experiments 2 and 3. This indicated spontaneous use of visual codes in immediate serial recall. It is suggested that any models of serial order memory should incorporate domain specificity.