The measurement of the thermoelectric properties of thin film thermoelectric materials has been an issue due to the difficulty and inaccuracy. In this work, we present a new model to simultaneously extract the Seebeck coefficient and thermal conductivity in the cross-sectional direction of thin film thermoelectric material. The proposed method uses a sandwich structure composed of a metal electrode/TE film/metal electrode and measures the external Seebeck coefficient at two different intervals on the metal electrode. A theoretical model enables us to extract the Seebeck coefficient and thermal conductivity of the thermoelectric material from the two external Seebeck coefficient measurement values. The proposed method is applied to screen-printed ZnSb film with copper electrodes and the measurement results were found to lie in a reasonable range. Given that this method is simple to use, it will contribute to the development of thin film thermoelectric devices.