In a semiconductor element having a compound semiconductor layer epitaxially grown on a silicon substrate, an object is to suppress generation of deficiency or problems of reliability deriving from the ends of the element that are generated when dividing into semiconductor devices by dicing. A compound semiconductor layer epitaxially grown on a silicon substrate is formed via a buffer layer made of aluminum nitride. In the periphery of the semiconductor device, a scribe lane is present to surround a semiconductor element region. Along the scribe lane, the aluminum nitride layer is covered with a coating film for protection against humidity and moisture.