A combined semiconductor rectifying device includes PN-junction silicon diode and Schottky barrier diode exhibiting a breakdown voltage higher than the breakdown voltage of PN-junction silicon diode, and Schottky barrier diode is made of a semiconductor, the band gap thereof is wider than the band gap of silicon. The combined semiconductor rectifying device exhibits a shortened reverse recovery time, low reverse leakage current characteristics and a high breakdown voltage, and is used advantageously in an electric power converter.