An accurate analytical model for regenerative chatter vibration in plunge cutting is proposed. Effects of the cross transfer function and the cutting force ratio on chatter stability are considered in the proposed model. Equivalent transfer function is defined, which is useful to understand those effects on chatter stability. Basic plunge cutting experiments were conducted to verify the proposed model. Although the critical widths of cut in the CW and CCW rotation processes were significantly different from each other in the experiment, even when the other conditions were the same, chatter stability limits were predicted accurately by the proposed model as compared with the conventional model.