Transcrystalline phenomenon was investigated in iPP/cellulose and PBS/cellulose systems. Cellulose allomorphs were prepared and the morphology was investgated at the interface of iPP/cellulose allomorphs and PBS/cellulose allomorphs by optical micrography. The cellulose fiber which had crystalline structure of cellulose II showed nucleating ability to iPP matrix. This observation is different from other works that no transcrystallinity was induced on Fortisan, other regenerated cellulose fiber and mecerized cellulose fiber. Cellulose allomorphs, also, showed nucleating ability to iPP and PBS. Nucleating ability of cellulose I, $III_{I}$, or $IV_{I}$ was higher than that of cellulose II, $III_{II}$, or $IV_{II}$. With increase in the isothermal crystallization temperature, nucleating ability of cellulose and growth rate of transcrystalline layer were decreased.