A Schottky np diode (SNPD) was fabricated on a 4H-SiC C-face epitaxial wafer, and its I-V characteristics were investigated. The diode showed a high blocking voltage of 300 V and ultralow on-resistance of 0.18 m Ω cm2 at a forward bias of 2.4 V. This value is almost the same as the resistance of the 4H-SiC bulk substrate, indicating that the resistance of the drift layer is almost zero and does not contribute to the observed on-resistance. As the temperature was increased, the forward I-V curve moved in parallel as the built-in bias shifted to a lower voltage due to the reduction in the barrier height of the np junction. This means that the resistance of SNPD above built-in bias is the same regardless of temperature. These results suggest that the diode is different from the conventional Schottky diodes and pn diodes. This diode has great potential for devices with both ultralow on-resistance and high blocking voltage.