In the present study, the wobbling motion of a single-flagellated bacterium was analyzed assuming that the bacterium consists of a cell body of prolate spheroid and flagellar helix, the axis of which is inclined to the major axis of the ellipsoid. The results were compared with those obtained by using dark field microscope. We investigated the relationship between the cell body shape of bacterium, inclined angle of flagellum, the angle of the wobbling motion to the promotion direction,the promotion distance during one cycle of wobbling motion and resistive coefficient. It was found that the promotion distance changes sensitively for the inclined angle of the axis of the flagellar helix as minur axis becomes small and the wobbling angle increses as the cell body shape approach from spheroid to the sphere. The variation of resitive coefficient gives qualitatively little effect on the promotion distance