<p>In end milling, in order to improve machining efficiency and accuracy, instantaneous rigid force model is widely used to predict cutting force and improve cutting conditions. The instantaneous rigid force model is well known as the practically simple model to predict cutting force. However this model requires the six parameters called cutting coefficients which have to be determined by the experimental milling operation. So several experimental milling operations are needed before cutting force prediction. In this study, a new instantaneous rigid force model based on oblique cutting is proposed. In this force model, the end milling process is modeled using the oblique cutting model. Therefore, cutting force prediction can be realized using only the one parameter such as shear angle instead of the six parameters such as cutting coefficients required for a conventional instantaneous rigid force model. The shear angle can be determined from tangential milling force or milling torque. And this force model is easier to apply for practical cutting force prediction, because time and effort to determine the parameter(s) before cutting force prediction. The validation of this force model compared with the conventional force model is performed. As the result, cutting forces predicted by the proposed force model has good agreement with the measured cutting forces. Also, the proposed force model has good performance in a wide range of cutting conditions compared with the conventional force model.</p>