The relationship between the emergence of language (word production, word comprehension) and the occurrence of symbolic behavior was longitudinally examined in 15 mentally retarded children who were nonverbal at the beginning of this study. Play behavior and word production were observed and word comprehension was assessed in task situation. Children who comprehended and produced object words increased the ratio of symbolic behaviors with progressing of the experimental sessions. In contrast, children who produced no object words did not show such behaviors so frequently. In the former case, the ratio of symbolic behavior at word production was higher than that at word comprehension. Three children who comprehended and produced at different experimental sessions, increasingly showed higher dimension of symbolic behavior (SYM2) rather than in the lower (SYM1). There were two associations regarding the occurrence of symbolic behavior at each language emergence: comprehension and production. Relations were also found between word production and SYM1, and between word production and SYM2.