In allelic model $X=(x_1,;x_2,;{cdots},;x_d)$, $$M_f(t)=f(p(t))-{int}_0^t;Lf(p(t))ds$$ is a P-martingale for diffusion operator L under the certain conditions. In this note, we try to apply diffusion processes for countable-allelic model in population genetic model and we can define a new diffusion operator $L^*$. Since the martingale problem for this operator $L^*$ is related to diffusion processes, we can define a integral which is combined with operator $L^*$ and a bilinar form $<{cdot},{cdot}>$. We can find properties for this integral using maximum principle.