A high-frequency power amplifier of the type to be mounted in an RF module for mobile phones having high-frequency power field effect transistors and gate protective diodes which are coupled between the gates and the sources of the high-frequency power field effect transistors. The gate protective diodes have an n type region formed over the main surface of a p type epitaxial layer, a first p type region formed at the center of the main surface of the n type region, a second p type region formed over the main surface of the epitaxial layer around the n type region from the periphery of the main surface of the n type region, and p+ type buried layers for coupling the second p type region to a substrate body. The distance between the end portions of the p+ type buried layers and the n+ type region is 7 μm or more.