It is particularly important to know the deformation behavior of the erythrocyte passing through a micro channel (MC) like the blood capillary. In this paper, the deformation behavior of an erythrocyte passing through the pseudo MC was calculated and observed by a two-dimensional numerical simulation of blood flow. The pseudo MC wall was created by assuming that the wall was one of the fluids which had no velocity at all times. The erythrocyte's movement and deformation were calculated by using an immersed boundary method. The following results were obtained by the simulation. An erythrocyte smoothly deformed and passed through the pseudo MC. In the pseudo MC, its shape changed to bullet-like shape and its moving velocity was almost constant. In addition, a narrow layer of only blood plasma, what we call the plasma layer, was formed between pseudo MC's wall surface and the erythrocyte membrane. It was possible that the plasma layer puts the erythrocyte into fluid lubrication. On the other hand, in our previous researches the deformation behavior of the erythrocyte passing through the MC was observed by experiments. The simulation results had good agreement particularly on an erythrocyte's deformed shape and process in MC with the experimental results.
