Measurements of electrical properties using the Van der Pauw technique have been made on the n-type and p-type silicon carbide single crystals and epitaxial layer having resistivity from 10-3 to 102 ohm-cm. Experiments on the selection of measuring conditions and comparison between the Van der Pauw method and the conventional method have been performed. It is found that the magnitude and stability of contact resistance greatly affect the measuring results. Among the pressure contacts studied, indium contact has the lowest contact resistance, while copper, tin, and phosphor-bronze contacts must be electrically formed before use. With different electrode materials and sample currents, the deviation of values obtained is about 2%. It is suggested that the sample current should be chosen in accordance with the resistivity and contact resistance of the specific sample. As compared with the conventional method, the Van der Pauw method can give higher precision and reproducibility. High temperature electrical properties of silicon carbide single crystals have been measured in a temperature range from room temperature to 1000°K, and the ionization energy of nitrogen donors is found to be 0.056 eV. Anomalous phenomena that result in experimental errors and their origins are discussed.